Merge pull request #388 from GetStream/core-nnbd

feat: Core nnbd

packages/stream_chat/lib/src/api/channel.dart

@@ -27,7 +27,7 @@ class Channel {
   }
 
   /// Create a channel client instance from a [ChannelState] object
-  Channel.fromState(this._client, ChannelState channelState) {
+  Channel.fromState(this._client, ChannelState channelState) : _extraData = {} {
     _cid = channelState.channel!.cid;
     _id = channelState.channel!.id;
     type = channelState.channel!.type;
@@ -45,9 +45,9 @@ class Channel {
 
   String? _id;
   String? _cid;
-  Map<String, dynamic>? _extraData;
+  Map<String, dynamic> _extraData;
 
-  set extraData(Map<String, dynamic>? extraData) {
+  set extraData(Map<String, dynamic> extraData) {
     if (_initializedCompleter.isCompleted) {
       throw Exception(
           'Once the channel is initialized you should use channel.update '
@@ -81,7 +81,7 @@ class Channel {
   /// Channel configuration as a stream
   Stream<ChannelConfig?>? get configStream {
     _checkInitialized();
-    return state?.channelStateStream.map((cs) => cs!.channel?.config);
+    return state?.channelStateStream.map((cs) => cs.channel?.config);
   }
 
   /// Channel user creator
@@ -93,7 +93,7 @@ class Channel {
   /// Channel user creator as a stream
   Stream<User?>? get createdByStream {
     _checkInitialized();
-    return state?.channelStateStream.map((cs) => cs!.channel?.createdBy);
+    return state?.channelStateStream.map((cs) => cs.channel?.createdBy);
   }
 
   /// Channel frozen status
@@ -105,7 +105,7 @@ class Channel {
   /// Channel frozen status as a stream
   Stream<bool?>? get frozenStream {
     _checkInitialized();
-    return state?.channelStateStream.map((cs) => cs!.channel?.frozen);
+    return state?.channelStateStream.map((cs) => cs.channel?.frozen);
   }
 
   /// Channel creation date
@@ -117,7 +117,7 @@ class Channel {
   /// Channel creation date as a stream
   Stream<DateTime?>? get createdAtStream {
     _checkInitialized();
-    return state?.channelStateStream.map((cs) => cs!.channel?.createdAt);
+    return state?.channelStateStream.map((cs) => cs.channel?.createdAt);
   }
 
   /// Channel last message date
@@ -131,7 +131,7 @@ class Channel {
   Stream<DateTime?>? get lastMessageAtStream {
     _checkInitialized();
 
-    return state?.channelStateStream.map((cs) => cs!.channel?.lastMessageAt);
+    return state?.channelStateStream.map((cs) => cs.channel?.lastMessageAt);
   }
 
   /// Channel updated date
@@ -145,7 +145,7 @@ class Channel {
   Stream<DateTime?>? get updatedAtStream {
     _checkInitialized();
 
-    return state?.channelStateStream.map((cs) => cs!.channel?.updatedAt);
+    return state?.channelStateStream.map((cs) => cs.channel?.updatedAt);
   }
 
   /// Channel deletion date
@@ -159,7 +159,7 @@ class Channel {
   Stream<DateTime?>? get deletedAtStream {
     _checkInitialized();
 
-    return state?.channelStateStream.map((cs) => cs!.channel?.deletedAt);
+    return state?.channelStateStream.map((cs) => cs.channel?.deletedAt);
   }
 
   /// Channel member count
@@ -173,7 +173,7 @@ class Channel {
   Stream<int?>? get memberCountStream {
     _checkInitialized();
 
-    return state?.channelStateStream.map((cs) => cs!.channel?.memberCount);
+    return state?.channelStateStream.map((cs) => cs.channel?.memberCount);
   }
 
   /// Channel id
@@ -189,13 +189,13 @@ class Channel {
   }
 
   /// Channel extra data
-  Map<String, dynamic>? get extraData =>
+  Map<String, dynamic> get extraData =>
       state?._channelState.channel?.extraData ?? _extraData;
 
   /// Channel extra data as a stream
   Stream<Map<String, dynamic>?>? get extraDataStream {
     _checkInitialized();
-    return state?.channelStateStream.map((cs) => cs!.channel?.extraData);
+    return state?.channelStateStream.map((cs) => cs.channel?.extraData);
   }
 
   /// The main Stream chat client
@@ -842,7 +842,7 @@ class Channel {
           messages: state?.messages?..remove(oldMessage),
         ));
       } else {
-        oldMessage = state!.threads!.values
+        oldMessage = state!.threads.values
             .expand((messages) => messages)
             .firstWhereOrNull((m) => m.id == messageId);
         if (oldMessage?.parentId != null) {
@@ -853,8 +853,8 @@ class Channel {
             state!.addMessage(parentMessage.copyWith(
                 replyCount: parentMessage.replyCount! - 1));
           }
-          state!.updateThreadInfo(oldMessage!.parentId,
+          state!.updateThreadInfo(oldMessage!.parentId!,
-              state!.threads![oldMessage.parentId!]!..remove(oldMessage));
+              state!.threads[oldMessage.parentId!]!..remove(oldMessage));
         }
       }
 
@@ -1028,7 +1028,7 @@ class Channel {
     })
       ..addAll(options);
 
-    if (_extraData != null) {
+    if (_extraData.isNotEmpty) {
       payload['data'] = _extraData;
     }
 
@@ -1333,7 +1333,7 @@ class ChannelClientState {
   final _subscriptions = <StreamSubscription>[];
 
   void _computeInitialUnread() {
-    final userRead = channelState?.read.firstWhereOrNull(
+    final userRead = channelState.read.firstWhereOrNull(
       (r) => r.user.id == _channel._client.state.user?.id,
     );
     if (userRead != null) {
@@ -1372,9 +1372,9 @@ class ChannelClientState {
   void _listenMemberAdded() {
     _subscriptions.add(_channel.on(EventType.memberAdded).listen((Event e) {
       final member = e.member;
-      updateChannelState(channelState!.copyWith(
+      updateChannelState(channelState.copyWith(
         members: [
-          ...channelState!.members,
+          ...channelState.members,
           member!,
         ],
       ));
@@ -1384,9 +1384,9 @@ class ChannelClientState {
   void _listenMemberRemoved() {
     _subscriptions.add(_channel.on(EventType.memberRemoved).listen((Event e) {
       final user = e.user;
-      updateChannelState(channelState!.copyWith(
+      updateChannelState(channelState.copyWith(
         members: List.from(
-            channelState!.members..removeWhere((m) => m.userId == user!.id)),
+            channelState.members..removeWhere((m) => m.userId == user!.id)),
       ));
     }));
   }
@@ -1394,7 +1394,7 @@ class ChannelClientState {
   void _listenChannelUpdated() {
     _subscriptions.add(_channel.on(EventType.channelUpdated).listen((Event e) {
       final channel = e.channel!;
-      updateChannelState(channelState!.copyWith(
+      updateChannelState(channelState.copyWith(
         channel: channel,
         members: channel.members,
       ));
@@ -1416,14 +1416,14 @@ class ChannelClientState {
   /// This flag should be managed by UI sdks.
   /// When false, any new message (received by WebSocket event
   /// - [EventType.messageNew]) will not be pushed on to message list.
-  bool get isUpToDate => _isUpToDateController.value!;
+  bool get isUpToDate => _isUpToDateController.value ?? true;
 
   set isUpToDate(bool isUpToDate) => _isUpToDateController.add(isUpToDate);
 
   /// [isUpToDate] flag count as a stream
-  Stream<bool?> get isUpToDateStream => _isUpToDateController.stream;
+  Stream<bool> get isUpToDateStream => _isUpToDateController.stream;
 
-  final BehaviorSubject<bool?> _isUpToDateController =
+  final BehaviorSubject<bool> _isUpToDateController =
       BehaviorSubject.seeded(true);
 
   /// The retry queue associated to this channel
@@ -1432,7 +1432,7 @@ class ChannelClientState {
   /// Retry failed message
   Future<void> retryFailedMessages() async {
     final failedMessages =
-        <Message>[...messages, ...threads!.values.expand((v) => v)]
+        <Message>[...messages, ...threads.values.expand((v) => v)]
             .where(
               (message) =>
                   message.status != MessageSendingStatus.sent &&
@@ -1549,7 +1549,7 @@ class ChannelClientState {
     }
 
     if (message.parentId != null) {
-      updateThreadInfo(message.parentId, [message]);
+      updateThreadInfo(message.parentId!, [message]);
     }
   }
 
@@ -1592,14 +1592,14 @@ class ChannelClientState {
 
   /// Channel message list as a stream
   Stream<List<Message>?> get messagesStream =>
-      channelStateStream.map((cs) => cs!.messages);
+      channelStateStream.map((cs) => cs.messages);
 
   /// Channel pinned message list
   List<Message>? get pinnedMessages => _channelState.pinnedMessages.toList();
 
   /// Channel pinned message list as a stream
   Stream<List<Message>?> get pinnedMessagesStream =>
-      channelStateStream.map((cs) => cs!.pinnedMessages.toList());
+      channelStateStream.map((cs) => cs.pinnedMessages.toList());
 
   /// Get channel last message
   Message? get lastMessage => _channelState.messages.isNotEmpty == true
@@ -1618,7 +1618,7 @@ class ChannelClientState {
   /// Channel members list as a stream
   Stream<List<Member>> get membersStream => CombineLatestStream.combine2<
           List<Member?>?, Map<String?, User?>, List<Member>>(
-        channelStateStream.map((cs) => cs!.members),
+        channelStateStream.map((cs) => cs.members),
         _channel.client.state.usersStream,
         (members, users) =>
             members!.map((e) => e!.copyWith(user: users[e.user!.id])).toList(),
@@ -1629,7 +1629,7 @@ class ChannelClientState {
 
   /// Channel watcher count as a stream
   Stream<int?> get watcherCountStream =>
-      channelStateStream.map((cs) => cs!.watcherCount);
+      channelStateStream.map((cs) => cs.watcherCount);
 
   /// Channel watchers list
   List<User> get watchers => _channelState.watchers
@@ -1639,7 +1639,7 @@ class ChannelClientState {
   /// Channel watchers list as a stream
   Stream<List<User>> get watchersStream => CombineLatestStream.combine2<
           List<User>?, Map<String?, User?>, List<User>>(
-        channelStateStream.map((cs) => cs!.watchers),
+        channelStateStream.map((cs) => cs.watchers),
         _channel.client.state.usersStream,
         (watchers, users) => watchers!.map((e) => users[e.id] ?? e).toList(),
       );
@@ -1648,8 +1648,7 @@ class ChannelClientState {
   List<Read>? get read => _channelState.read;
 
   /// Channel read list as a stream
-  Stream<List<Read>?> get readStream =>
+  Stream<List<Read>?> get readStream => channelStateStream.map((cs) => cs.read);
-      channelStateStream.map((cs) => cs!.read);
 
   final BehaviorSubject<int> _unreadCountController = BehaviorSubject.seeded(0);
 
@@ -1672,21 +1671,20 @@ class ChannelClientState {
   }
 
   /// Update threads with updated information about messages
-  void updateThreadInfo(String? parentId, List<Message>? messages) {
+  void updateThreadInfo(String parentId, List<Message> messages) {
-    final newThreads = Map<String?, List<Message>?>.from(threads!);
+    final newThreads = Map<String, List<Message>>.from(threads);
 
     if (newThreads.containsKey(parentId)) {
       newThreads[parentId] = [
         ...newThreads[parentId]
-                ?.where((newMessage) =>
+                ?.where(
-                    !messages!.any((m) => m.id == newMessage.id))
+                    (newMessage) => !messages.any((m) => m.id == newMessage.id))
                 .toList() ??
             [],
-        ...messages!,
+        ...messages,
       ];
 
-      newThreads[parentId]!
+      newThreads[parentId]!.sort(_sortByCreatedAt);
-          .sort(_sortByCreatedAt as int Function(Message, Message)?);
     } else {
       newThreads[parentId] = messages;
     }
@@ -1713,7 +1711,7 @@ class ChannelClientState {
                   .any((newMessage) => newMessage.id == m.id) !=
               true)
           .toList(),
-    ]..sort(_sortByCreatedAt as int Function(Message, Message)?);
+    ]..sort(_sortByCreatedAt);
 
     final newWatchers = <User>[
       ...updatedState.watchers,
@@ -1752,27 +1750,17 @@ class ChannelClientState {
     );
   }
 
-  int? _sortByCreatedAt(a, b) {
+  int _sortByCreatedAt(Message a, Message b) =>
-    if (a.createdAt == null) {
+      a.createdAt.compareTo(b.createdAt);
-      return 1;
-    }
-
-    if (b.createdAt == null) {
-      return -1;
-    }
-
-    return a.createdAt.compareTo(b.createdAt);
-  }
 
   /// The channel state related to this client
   ChannelState get _channelState => _channelStateController.value!;
 
   /// The channel state related to this client as a stream
-  Stream<ChannelState?> get channelStateStream =>
+  Stream<ChannelState> get channelStateStream => _channelStateController.stream;
-      _channelStateController.stream;
 
   /// The channel state related to this client
-  ChannelState? get channelState => _channelStateController.value;
+  ChannelState get channelState => _channelStateController.value!;
   late BehaviorSubject<ChannelState> _channelStateController;
 
   final Debounce _debouncedUpdatePersistenceChannelState;
@@ -1783,33 +1771,33 @@ class ChannelClientState {
   }
 
   /// The channel threads related to this channel
-  Map<String, List<Message>>? get threads => _threadsController.value
+  Map<String, List<Message>> get threads =>
-      ?.map((key, value) => MapEntry(key ?? '', value ?? []));
+      _threadsController.value!.map((key, value) => MapEntry(key, value));
 
   /// The channel threads related to this channel as a stream
-  Stream<Map<String?, List<Message>?>> get threadsStream =>
+  Stream<Map<String, List<Message>>> get threadsStream =>
       _threadsController.stream;
-  final BehaviorSubject<Map<String?, List<Message>?>> _threadsController =
+  final BehaviorSubject<Map<String, List<Message>>> _threadsController =
       BehaviorSubject.seeded({});
 
-  set _threads(Map<String?, List<Message>?> v) {
+  set _threads(Map<String, List<Message>> v) {
     _channel._client.chatPersistenceClient?.updateMessages(
       _channel.cid!,
-      v.values.expand((v) => v!).toList(),
+      v.values.expand((v) => v).toList(),
     );
     _threadsController.add(v);
   }
 
   /// Channel related typing users last value
-  List<User>? get typingEvents => _typingEventsController.value as List<User>?;
+  List<User> get typingEvents => _typingEventsController.value!;
 
   /// Channel related typing users stream
-  Stream<List<User?>> get typingEventsStream => _typingEventsController.stream;
+  Stream<List<User>> get typingEventsStream => _typingEventsController.stream;
-  final BehaviorSubject<List<User?>> _typingEventsController =
+  final BehaviorSubject<List<User>> _typingEventsController =
       BehaviorSubject.seeded([]);
 
   final Channel _channel;
-  final Map<User?, DateTime> _typings = {};
+  final Map<User, DateTime> _typings = {};
 
   void _listenTypingEvents() {
     if (_channelState.channel?.config.typingEvents == false) {
@@ -1820,9 +1808,12 @@ class ChannelClientState {
       ..add(
         _channel.on(EventType.typingStart).listen(
           (event) {
-            if (event.user!.id != _channel.client.state.user!.id) {
+            if (event.user != null) {
-              _typings[event.user] = DateTime.now();
+              final user = event.user!;
-              _typingEventsController.add(_typings.keys.toList());
+              if (user.id != _channel.client.state.user?.id) {
+                _typings[user] = DateTime.now();
+                _typingEventsController.add(_typings.keys.toList());
+              }
             }
           },
         ),
@@ -1830,9 +1821,12 @@ class ChannelClientState {
       ..add(
         _channel.on(EventType.typingStop).listen(
           (event) {
-            if (event.user!.id != _channel.client.state.user!.id) {
+            if (event.user != null) {
-              _typings.remove(event.user);
+              final user = event.user!;
-              _typingEventsController.add(_typings.keys.toList());
+              if (user.id != _channel.client.state.user?.id) {
+                _typings.remove(event.user);
+                _typingEventsController.add(_typings.keys.toList());
+              }
             }
           },
         ),
@@ -1888,7 +1882,7 @@ class ChannelClientState {
   void _startCleaningPinnedMessages() {
     _pinnedMessagesTimer = Timer.periodic(const Duration(seconds: 30), (_) {
       final now = DateTime.now();
-      var expiredMessages = channelState!.pinnedMessages
+      var expiredMessages = channelState.pinnedMessages
           .where((m) => m.pinExpires?.isBefore(now) == true)
           .toList();
       if (expiredMessages.isNotEmpty) {

packages/stream_chat/lib/src/client.dart

@@ -780,10 +780,11 @@ class StreamChatClient {
     PaginationParams paginationParams = const PaginationParams(),
   }) async {
     final offlineChannels = (await _chatPersistenceClient?.getChannelStates(
-      filter: filter,
+          filter: filter,
-      sort: sort,
+          sort: sort,
-      paginationParams: paginationParams,
+          paginationParams: paginationParams,
-    ))!;
+        )) ??
+        [];
     final updatedData = _mapChannelStateToChannel(offlineChannels);
     state.channels = updatedData.key;
     return updatedData.value;
@@ -1193,7 +1194,7 @@ class StreamChatClient {
   Channel channel(
     String type, {
     String? id,
-    Map<String, dynamic>? extraData,
+    Map<String, dynamic> extraData = const {},
   }) {
     if (id != null && state.channels?.containsKey('$type:$id') == true) {
       if (state.channels!['$type:$id'] != null) {

packages/stream_chat/lib/src/models/channel_model.dart

@@ -27,7 +27,7 @@ class ChannelModel {
         createdAt = createdAt ?? DateTime.now(),
         updatedAt = updatedAt ?? DateTime.now(),
         assert(
-          cid != null || (id != null && type != null),
+          (cid != null && cid.contains(':')) || (id != null && type != null),
           'provide either a cid or an id and type',
         ),
         id = id ?? cid!.split(':')[1],

packages/stream_chat/lib/src/models/own_user.dart

@@ -17,8 +17,8 @@ class OwnUser extends User {
     this.totalUnreadCount = 0,
     this.unreadChannels,
     this.channelMutes = const [],
-    String id = '',
+    required String id,
-    String role = '',
+    String? role,
     DateTime? createdAt,
     DateTime? updatedAt,
     DateTime? lastActive,

packages/stream_chat/lib/src/models/own_user.g.dart

@@ -23,7 +23,7 @@ OwnUser _$OwnUserFromJson(Map<String, dynamic> json) {
             .toList() ??
         [],
     id: json['id'] as String,
-    role: json['role'] as String,
+    role: json['role'] as String?,
     createdAt: json['created_at'] == null
         ? null
         : DateTime.parse(json['created_at'] as String),

packages/stream_chat/lib/src/models/user.dart

@@ -81,7 +81,7 @@ class User {
   int get hashCode => id.hashCode;
 
   /// Shortcut for user name
-  String? get name =>
+  String get name =>
       (extraData.containsKey('name') == true && extraData['name'] != '')
           ? extraData['name']
           : id;

packages/stream_chat/lib/stream_chat.dart

@@ -3,6 +3,7 @@ library stream_chat;
 export 'package:async/async.dart';
 export 'package:dio/src/dio_error.dart';
 export 'package:dio/src/multipart_file.dart';
+export 'package:dio/src/options.dart';
 export 'package:dio/src/options.dart' show ProgressCallback;
 export 'package:logging/logging.dart' show Logger, Level;
 

packages/stream_chat/test/src/api/channel_test.dart

@@ -516,7 +516,7 @@ void main() {
       );
       await channelClient.watch();
 
-      final event = Event(type: EventType.any);
+      final event = const Event(type: EventType.any);
 
       when(
         () => mockDio.post<String>(
@@ -564,7 +564,7 @@ void main() {
       );
       await channelClient.watch();
 
-      final event = Event(type: EventType.typingStart);
+      final event = const Event(type: EventType.typingStart);
 
       when(
         () => mockDio.post<String>(
@@ -610,7 +610,7 @@ void main() {
       );
       await channelClient.watch();
 
-      final event = Event(type: EventType.typingStop);
+      final event = const Event(type: EventType.typingStop);
 
       when(
         () => mockDio.post<String>(
@@ -901,8 +901,10 @@ void main() {
             'presence': true,
           };
 
-          when(() => mockDio.post<String>('/channels/messaging/query',
+          when(() => mockDio.post<String>(
-              data: options)).thenAnswer(
+                '/channels/messaging/query',
+                data: options,
+              )).thenAnswer(
             (_) async => Response(
               data: r'''
             {
@@ -1198,8 +1200,10 @@ void main() {
 
           final response = await channelClient.query(options: options);
 
-          verify(() => mockDio.post<String>('/channels/messaging/query',
+          verify(() => mockDio.post<String>(
-              data: options)).called(1);
+                '/channels/messaging/query',
+                data: options,
+              )).called(1);
           expect(channelClient.id, response.channel?.id);
           expect(channelClient.cid, response.channel?.cid);
         });

packages/stream_chat_flutter_core/example/lib/main.dart

@@ -38,8 +38,8 @@ class StreamExample extends StatelessWidget {
   /// If you'd prefer using pre-made UI widgets for your app, please see our other
   /// package, `stream_chat_flutter`.
   const StreamExample({
-    Key key,
+    Key? key,
-    @required this.client,
+    required this.client,
   }) : super(key: key);
 
   /// Instance of Stream Client.
@@ -55,7 +55,7 @@ class StreamExample extends StatelessWidget {
       home: HomeScreen(),
       builder: (context, child) => StreamChatCore(
         client: client,
-        child: child,
+        child: child!,
       ),
     );
   }
@@ -82,7 +82,7 @@ class HomeScreen extends StatelessWidget {
             'type': 'messaging',
             'members': {
               r'$in': [
-                StreamChatCore.of(context).user.id,
+                StreamChatCore.of(context).user!.id,
               ]
             }
           },
@@ -100,10 +100,13 @@ class HomeScreen extends StatelessWidget {
               ),
             );
           },
-          errorBuilder: (BuildContext context, dynamic error) {
+          errorBuilder: (
+            BuildContext context,
+            dynamic error,
+          ) {
             return Center(
               child: Text(
-                  'Oh no, something went wrong. Please check your config.'),
+                  'Oh no, something went wrong. Please check your config. ${error}'),
             );
           },
           listBuilder: (
@@ -112,20 +115,20 @@ class HomeScreen extends StatelessWidget {
           ) =>
               LazyLoadScrollView(
             onEndOfPage: () async {
-              channelListController.paginateData();
+              channelListController.paginateData!();
             },
             child: ListView.builder(
               itemCount: channels.length,
               itemBuilder: (BuildContext context, int index) {
                 final _item = channels[index];
                 return ListTile(
-                  title: Text(_item.name),
+                  title: Text(_item.name!),
-                  subtitle: StreamBuilder<Message>(
+                  subtitle: StreamBuilder<Message?>(
-                    stream: _item.state.lastMessageStream,
+                    stream: _item.state!.lastMessageStream,
-                    initialData: _item.state.lastMessage,
+                    initialData: _item.state!.lastMessage,
                     builder: (context, snapshot) {
                       if (snapshot.hasData) {
-                        return Text(snapshot.data.text);
+                        return Text(snapshot.data!.text!);
                       }
 
                       return SizedBox();
@@ -169,8 +172,8 @@ class MessageScreen extends StatefulWidget {
 }
 
 class _MessageScreenState extends State<MessageScreen> {
-  TextEditingController _controller;
+  late final TextEditingController _controller;
-  ScrollController _scrollController;
+  late final ScrollController _scrollController;
   final messageListController = MessageListController();
 
   @override
@@ -203,11 +206,11 @@ class _MessageScreenState extends State<MessageScreen> {
     return Scaffold(
       appBar: AppBar(
         title: StreamBuilder<List<User>>(
-          initialData: channel.state.typingEvents,
+          initialData: channel.state?.typingEvents,
-          stream: channel.state.typingEventsStream,
+          stream: channel.state?.typingEventsStream,
           builder: (context, snapshot) {
-            if (snapshot.hasData && snapshot.data.isNotEmpty) {
+            if (snapshot.hasData && snapshot.data!.isNotEmpty) {
-              return Text('${snapshot.data.first.name} is typing...');
+              return Text('${snapshot.data!.first.name} is typing...');
             }
             return SizedBox();
           },
@@ -219,9 +222,10 @@ class _MessageScreenState extends State<MessageScreen> {
             Expanded(
               child: LazyLoadScrollView(
                 onEndOfPage: () async {
-                  messageListController.paginateData();
+                  messageListController.paginateData!();
                 },
                 child: MessageListCore(
+                  messageListController: messageListController,
                   emptyBuilder: (BuildContext context) {
                     return Center(
                       child: Text('Nothing here yet'),
@@ -247,12 +251,12 @@ class _MessageScreenState extends State<MessageScreen> {
                       itemBuilder: (BuildContext context, int index) {
                         final item = messages[index];
                         final client = StreamChatCore.of(context).client;
-                        if (item.user.id == client.uid) {
+                        if (item.user!.id == client.uid) {
                           return Align(
                             alignment: Alignment.centerRight,
                             child: Padding(
                               padding: const EdgeInsets.all(8.0),
-                              child: Text(item.text),
+                              child: Text(item.text!),
                             ),
                           );
                         } else {
@@ -260,7 +264,7 @@ class _MessageScreenState extends State<MessageScreen> {
                             alignment: Alignment.centerLeft,
                             child: Padding(
                               padding: const EdgeInsets.all(8.0),
-                              child: Text(item.text),
+                              child: Text(item.text!),
                             ),
                           );
                         }
@@ -268,7 +272,7 @@ class _MessageScreenState extends State<MessageScreen> {
                     );
                   },
                   errorWidgetBuilder: (BuildContext context, error) {
-                    print(error?.toString());
+                    print(error.toString());
                     return Center(
                       child: SizedBox(
                         height: 100.0,
@@ -282,7 +286,7 @@ class _MessageScreenState extends State<MessageScreen> {
               ),
             ),
             Padding(
-              padding: const EdgeInsets.all(8.0),
+              padding: const EdgeInsets.all(8),
               child: Row(
                 children: [
                   Expanded(
@@ -303,12 +307,14 @@ class _MessageScreenState extends State<MessageScreen> {
                           await channel.sendMessage(
                             Message(text: _controller.value.text),
                           );
-                          _controller.clear();
+                          if (mounted) {
-                          _updateList();
+                            _controller.clear();
+                            _updateList();
+                          }
                         }
                       },
                       child: const Padding(
-                        padding: EdgeInsets.all(8.0),
+                        padding: EdgeInsets.all(8),
                         child: Center(
                           child: Icon(
                             Icons.send,
@@ -332,12 +338,12 @@ class _MessageScreenState extends State<MessageScreen> {
 /// below, we add two simple extensions to the [StreamChatClient] and [Channel].
 extension on StreamChatClient {
   /// Fetches the current user id.
-  String get uid => state.user.id;
+  String get uid => state.user!.id;
 }
 
 extension on Channel {
   /// Fetches the name of the channel by accessing [extraData] or [cid].
-  String get name {
+  String? get name {
     final _channelName = extraData['name'];
     if (_channelName != null) {
       return _channelName;

packages/stream_chat_flutter_core/example/pubspec.yaml

@@ -18,7 +18,7 @@ publish_to: 'none' # Remove this line if you wish to publish to pub.dev
 version: 1.0.0+1
 
 environment:
-  sdk: ">=2.7.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
   flutter:

packages/stream_chat_flutter_core/lib/src/channel_list_core.dart

@@ -57,11 +57,11 @@ import 'package:stream_chat_flutter_core/src/typedef.dart';
 class ChannelListCore extends StatefulWidget {
   /// Instantiate a new ChannelListView
   const ChannelListCore({
-    Key key,
+    Key? key,
-    @required this.errorBuilder,
+    required this.errorBuilder,
-    @required this.emptyBuilder,
+    required this.emptyBuilder,
-    @required this.loadingBuilder,
+    required this.loadingBuilder,
-    @required this.listBuilder,
+    required this.listBuilder,
     this.filter,
     this.options,
     this.sort,
@@ -69,29 +69,13 @@ class ChannelListCore extends StatefulWidget {
       limit: 25,
     ),
     this.channelListController,
-  })  : assert(
+  }) : super(key: key);
-          errorBuilder != null,
-          'Parameter errorBuilder should not be null',
-        ),
-        assert(
-          emptyBuilder != null,
-          'Parameter emptyBuilder should not be null',
-        ),
-        assert(
-          loadingBuilder != null,
-          'Parameter loadingBuilder should not be null',
-        ),
-        assert(
-          listBuilder != null,
-          'Parameter listBuilder should not be null',
-        ),
-        super(key: key);
 
   /// A [ChannelListController] allows reloading and pagination.
   /// Use [ChannelListController.loadData] and
   /// [ChannelListController.paginateData] respectively for reloading and
   /// pagination.
-  final ChannelListController channelListController;
+  final ChannelListController? channelListController;
 
   /// The builder that will be used in case of error
   final ErrorBuilder errorBuilder;
@@ -108,20 +92,20 @@ class ChannelListCore extends StatefulWidget {
   /// The query filters to use.
   /// You can query on any of the custom fields you've defined on the [Channel].
   /// You can also filter other built-in channel fields.
-  final Map<String, dynamic> filter;
+  final Map<String, dynamic>? filter;
 
   /// Query channels options.
   ///
   /// state: if true returns the Channel state
   /// watch: if true listen to changes to this Channel in real time.
-  final Map<String, dynamic> options;
+  final Map<String, dynamic>? options;
 
   /// The sorting used for the channels matching the filters.
   /// Sorting is based on field and direction, multiple sorting options can be
   /// provided.
   /// You can sort based on last_updated, last_message_at, updated_at, created
   /// _at or member_count. Direction can be ascending or descending.
-  final List<SortOption<ChannelModel>> sort;
+  final List<SortOption<ChannelModel>>? sort;
 
   /// Pagination parameters
   /// limit: the number of channels to return (max is 30)
@@ -149,12 +133,12 @@ class ChannelListCoreState extends State<ChannelListCore> {
         stream: channelsBlocState.channelsStream,
         builder: (context, snapshot) {
           if (snapshot.hasError) {
-            return widget.errorBuilder(context, snapshot.error);
+            return widget.errorBuilder(context, snapshot.error!);
           }
           if (!snapshot.hasData) {
             return widget.loadingBuilder(context);
           }
-          final channels = snapshot.data;
+          final channels = snapshot.data!;
           if (channels.isEmpty) {
             return widget.emptyBuilder(context);
           }
@@ -186,7 +170,7 @@ class ChannelListCoreState extends State<ChannelListCore> {
     );
   }
 
-  StreamSubscription<Event> _subscription;
+  late StreamSubscription<Event> _subscription;
 
   @override
   void initState() {
@@ -203,8 +187,8 @@ class ChannelListCoreState extends State<ChannelListCore> {
         .listen((event) => loadData());
 
     if (widget.channelListController != null) {
-      widget.channelListController.loadData = loadData;
+      widget.channelListController!.loadData = loadData;
-      widget.channelListController.paginateData = paginateData;
+      widget.channelListController!.paginateData = paginateData;
     }
   }
 
@@ -215,8 +199,8 @@ class ChannelListCoreState extends State<ChannelListCore> {
     if (widget.filter?.toString() != oldWidget.filter?.toString() ||
         jsonEncode(widget.sort) != jsonEncode(oldWidget.sort) ||
         widget.options?.toString() != oldWidget.options?.toString() ||
-        widget.pagination?.toJson()?.toString() !=
+        widget.pagination.toJson().toString() !=
-            oldWidget.pagination?.toJson()?.toString()) {
+            oldWidget.pagination.toJson().toString()) {
       loadData();
     }
   }
@@ -233,10 +217,10 @@ class ChannelListCoreState extends State<ChannelListCore> {
 class ChannelListController {
   /// This function calls Stream's servers to load a list of channels.
   /// If there is existing data, calling this function causes a reload.
-  AsyncCallback loadData;
+  AsyncCallback? loadData;
 
   /// This function is used to load another page of data. Note, [loadData]
   /// should be used to populate the initial page of data. Calling
   /// [paginateData] performs a query to load subsequent pages.
-  AsyncCallback paginateData;
+  AsyncCallback? paginateData;
 }

packages/stream_chat_flutter_core/lib/src/channels_bloc.dart

@@ -20,13 +20,12 @@ class ChannelsBloc extends StatefulWidget {
   /// Creates a new [ChannelsBloc]. The parameter [child] must be supplied and
   /// not null.
   const ChannelsBloc({
-    Key key,
+    Key? key,
-    @required this.child,
+    required this.child,
     this.lockChannelsOrder = false,
     this.channelsComparator,
     this.shouldAddChannel,
-  })  : assert(child != null, 'Parameter child should not be null.'),
+  }) : super(key: key);
-        super(key: key);
 
   /// The widget child
   final Widget child;
@@ -36,18 +35,18 @@ class ChannelsBloc extends StatefulWidget {
   final bool lockChannelsOrder;
 
   /// Comparator used to sort the channels when a message.new event is received
-  final Comparator<Channel> channelsComparator;
+  final Comparator<Channel>? channelsComparator;
 
   /// Function used to evaluate if a channel should be added to the list when a
   /// message.new event is received
-  final bool Function(Event) shouldAddChannel;
+  final bool Function(Event)? shouldAddChannel;
 
   @override
   ChannelsBlocState createState() => ChannelsBlocState();
 
   /// Use this method to get the current [ChannelsBlocState] instance
   static ChannelsBlocState of(BuildContext context) {
-    ChannelsBlocState streamChatState;
+    ChannelsBlocState? streamChatState;
 
     streamChatState = context.findAncestorStateOfType<ChannelsBlocState>();
 
@@ -69,14 +68,15 @@ class ChannelsBlocState extends State<ChannelsBloc>
   }
 
   /// The current channel list
-  List<Channel> get channels => _channelsController.value;
+  List<Channel>? get channels => _channelsController.value;
 
   /// The current channel list as a stream
   Stream<List<Channel>> get channelsStream => _channelsController.stream;
 
   final _queryChannelsLoadingController = BehaviorSubject.seeded(false);
 
-  final _channelsController = BehaviorSubject<List<Channel>>();
+  final BehaviorSubject<List<Channel>> _channelsController =
+      BehaviorSubject<List<Channel>>();
 
   /// The stream notifying the state of queryChannel call
   Stream<bool> get queryChannelsLoading =>
@@ -88,10 +88,10 @@ class ChannelsBlocState extends State<ChannelsBloc>
 
   /// Calls [client.queryChannels] updating [queryChannelsLoading] stream
   Future<void> queryChannels({
-    Map<String, dynamic> filter,
+    Map<String, dynamic>? filter,
-    List<SortOption<ChannelModel>> sortOptions,
+    List<SortOption<ChannelModel>>? sortOptions,
-    PaginationParams paginationParams,
+    PaginationParams paginationParams = const PaginationParams(limit: 30),
-    Map<String, dynamic> options,
+    Map<String, dynamic>? options,
   }) async {
     final client = StreamChatCore.of(context).client;
 
@@ -104,9 +104,7 @@ class ChannelsBlocState extends State<ChannelsBloc>
     }
 
     try {
-      final clear = paginationParams == null ||
+      final clear = paginationParams.offset == 0;
-          paginationParams.offset == null ||
-          paginationParams.offset == 0;
       final oldChannels = List<Channel>.from(channels ?? []);
       var newChannels = <Channel>[];
       await for (final channels in client.queryChannels(
@@ -123,7 +121,7 @@ class ChannelsBlocState extends State<ChannelsBloc>
           _channelsController.add(temp);
         }
         if (_channelsController.hasValue &&
-            _queryChannelsLoadingController.value) {
+            _queryChannelsLoadingController.value!) {
           _queryChannelsLoadingController.sink.add(false);
         }
       }
@@ -162,9 +160,9 @@ class ChannelsBlocState extends State<ChannelsBloc>
             newChannels.insert(0, _hiddenChannels[hiddenIndex]);
             _hiddenChannels.removeAt(hiddenIndex);
           } else {
-            if (client.state?.channels != null &&
+            if (client.state.channels != null &&
-                client.state?.channels[e.cid] != null) {
+                client.state.channels?[e.cid] != null) {
-              newChannels.insert(0, client.state.channels[e.cid]);
+              newChannels.insert(0, client.state.channels![e.cid]!);
             }
           }
         }
@@ -195,7 +193,7 @@ class ChannelsBlocState extends State<ChannelsBloc>
       // ignore: cascade_invocations
       final channel = e.channel;
       _channelsController.add(List.from(
-          (channels ?? [])..removeWhere((c) => c.cid == channel.cid)));
+          (channels ?? [])..removeWhere((c) => c.cid == channel?.cid)));
     }));
   }
 

packages/stream_chat_flutter_core/lib/src/lazy_load_scroll_view.dart

@@ -9,34 +9,33 @@ class LazyLoadScrollView extends StatefulWidget {
   /// Creates a new instance of [LazyLoadScrollView]. The parameter [child]
   /// must be supplied and not null.
   const LazyLoadScrollView({
-    Key key,
+    Key? key,
-    @required this.child,
+    required this.child,
     this.onStartOfPage,
     this.onEndOfPage,
     this.onPageScrollStart,
     this.onPageScrollEnd,
     this.onInBetweenOfPage,
     this.scrollOffset = 100,
-  })  : assert(child != null, 'Parameter child should not be null'),
+  }) : super(key: key);
-        super(key: key);
 
   /// The [Widget] that this widget watches for changes on
   final Widget child;
 
   /// Called when the [child] reaches the start of the list
-  final AsyncCallback onStartOfPage;
+  final AsyncCallback? onStartOfPage;
 
   /// Called when the [child] reaches the end of the list
-  final AsyncCallback onEndOfPage;
+  final AsyncCallback? onEndOfPage;
 
   /// Called when the list scrolling starts
-  final VoidCallback onPageScrollStart;
+  final VoidCallback? onPageScrollStart;
 
   /// Called when the list scrolling ends
-  final VoidCallback onPageScrollEnd;
+  final VoidCallback? onPageScrollEnd;
 
   /// Called every time the [child] is in-between the list
-  final VoidCallback onInBetweenOfPage;
+  final VoidCallback? onInBetweenOfPage;
 
   /// The offset to take into account when triggering [onEndOfPage]/[onStartOfPage] in pixels
   final double scrollOffset;
@@ -46,7 +45,7 @@ class LazyLoadScrollView extends StatefulWidget {
 }
 
 class _LazyLoadScrollViewState extends State<LazyLoadScrollView> {
-  _LoadingStatus _loadMoreStatus = _LoadingStatus.stable;
+  var _loadMoreStatus = _LoadingStatus.stable;
   double _scrollPosition = 0;
 
   @override
@@ -59,13 +58,13 @@ class _LazyLoadScrollViewState extends State<LazyLoadScrollView> {
   bool _onNotification(ScrollNotification notification) {
     if (notification is ScrollStartNotification) {
       if (widget.onPageScrollStart != null) {
-        widget.onPageScrollStart();
+        widget.onPageScrollStart!();
         return true;
       }
     }
     if (notification is ScrollEndNotification) {
       if (widget.onPageScrollEnd != null) {
-        widget.onPageScrollEnd();
+        widget.onPageScrollEnd!();
         return true;
       }
     }
@@ -73,12 +72,12 @@ class _LazyLoadScrollViewState extends State<LazyLoadScrollView> {
       final pixels = notification.metrics.pixels;
       final maxScrollExtent = notification.metrics.maxScrollExtent;
       final minScrollExtent = notification.metrics.minScrollExtent;
-      final scrollOffset = widget.scrollOffset ?? 0;
+      final scrollOffset = widget.scrollOffset;
 
       if (pixels > (minScrollExtent + scrollOffset) &&
           pixels < (maxScrollExtent - scrollOffset)) {
         if (widget.onInBetweenOfPage != null) {
-          widget.onInBetweenOfPage();
+          widget.onInBetweenOfPage!();
           return true;
         }
       }
@@ -114,10 +113,10 @@ class _LazyLoadScrollViewState extends State<LazyLoadScrollView> {
   }
 
   void _onEndOfPage() {
-    if (_loadMoreStatus != null && _loadMoreStatus == _LoadingStatus.stable) {
+    if (_loadMoreStatus == _LoadingStatus.stable) {
       if (widget.onEndOfPage != null) {
         _loadMoreStatus = _LoadingStatus.loading;
-        widget.onEndOfPage().whenComplete(() {
+        widget.onEndOfPage!().whenComplete(() {
           _loadMoreStatus = _LoadingStatus.stable;
         });
       }
@@ -125,10 +124,10 @@ class _LazyLoadScrollViewState extends State<LazyLoadScrollView> {
   }
 
   void _onStartOfPage() {
-    if (_loadMoreStatus != null && _loadMoreStatus == _LoadingStatus.stable) {
+    if (_loadMoreStatus == _LoadingStatus.stable) {
       if (widget.onStartOfPage != null) {
         _loadMoreStatus = _LoadingStatus.loading;
-        widget.onStartOfPage().whenComplete(() {
+        widget.onStartOfPage!().whenComplete(() {
           _loadMoreStatus = _LoadingStatus.stable;
         });
       }

packages/stream_chat_flutter_core/lib/src/message_list_core.dart

@@ -61,30 +61,20 @@ import 'package:stream_chat_flutter_core/src/typedef.dart';
 class MessageListCore extends StatefulWidget {
   /// Instantiate a new [MessageListView].
   const MessageListCore({
-    Key key,
+    Key? key,
-    @required this.loadingBuilder,
+    required this.loadingBuilder,
-    @required this.emptyBuilder,
+    required this.emptyBuilder,
-    @required this.messageListBuilder,
+    required this.messageListBuilder,
-    @required this.errorWidgetBuilder,
+    required this.errorWidgetBuilder,
     this.showScrollToBottom = true,
     this.parentMessage,
     this.messageListController,
     this.messageFilter,
-  })  : assert(loadingBuilder != null, 'loadingBuilder should not be null'),
+  }) : super(key: key);
-        assert(emptyBuilder != null, 'emptyBuilder should not be null'),
-        assert(
-          messageListBuilder != null,
-          'messageListBuilder should not be null',
-        ),
-        assert(
-          errorWidgetBuilder != null,
-          'errorWidgetBuilder should not be null',
-        ),
-        super(key: key);
 
   /// A [MessageListController] allows pagination.
   /// Use [ChannelListController.paginateData] pagination.
-  final MessageListController messageListController;
+  final MessageListController? messageListController;
 
   /// Function called when messages are fetched
   final Widget Function(BuildContext, List<Message>) messageListBuilder;
@@ -108,10 +98,10 @@ class MessageListCore extends StatefulWidget {
 
   /// If the current message belongs to a `thread`, this property represents the
   /// first message or the parent of the conversation.
-  final Message parentMessage;
+  final Message? parentMessage;
 
   /// Predicate used to filter messages
-  final bool Function(Message) messageFilter;
+  final bool Function(Message)? messageFilter;
 
   @override
   MessageListCoreState createState() => MessageListCoreState();
@@ -119,41 +109,44 @@ class MessageListCore extends StatefulWidget {
 
 /// The current state of the [MessageListCore].
 class MessageListCoreState extends State<MessageListCore> {
-  StreamChannelState _streamChannel;
+  late StreamChannelState _streamChannel;
 
-  bool get _upToDate => _streamChannel.channel.state.isUpToDate;
+  bool get _upToDate => _streamChannel.channel.state?.isUpToDate ?? true;
 
   bool get _isThreadConversation => widget.parentMessage != null;
 
-  OwnUser get _currentUser => _streamChannel.channel.client.state.user;
+  OwnUser? get _currentUser => _streamChannel.channel.client.state.user;
 
   var _messages = <Message>[];
 
   @override
   Widget build(BuildContext context) {
     final messagesStream = _isThreadConversation
-        ? _streamChannel.channel.state.threadsStream
+        ? _streamChannel.channel.state?.threadsStream
-            .where((threads) => threads.containsKey(widget.parentMessage.id))
+            .where((threads) => threads.containsKey(widget.parentMessage!.id))
-            .map((threads) => threads[widget.parentMessage.id])
+            .map((threads) => threads[widget.parentMessage!.id])
         : _streamChannel.channel.state?.messagesStream;
 
     bool defaultFilter(Message m) {
-      final isMyMessage = m.user.id == _currentUser.id;
+      final isMyMessage = m.user?.id == _currentUser?.id;
       final isDeletedOrShadowed = m.isDeleted == true || m.shadowed == true;
       if (isDeletedOrShadowed && !isMyMessage) return false;
       return true;
     }
 
-    return StreamBuilder<List<Message>>(
+    return StreamBuilder<List<Message>?>(
       stream: messagesStream?.map((messages) =>
-          messages?.where(widget.messageFilter ?? defaultFilter)?.toList()),
+          messages?.where(widget.messageFilter ?? defaultFilter).toList(
+                growable: false,
+              )),
       builder: (context, snapshot) {
         if (snapshot.hasError) {
-          return widget.errorWidgetBuilder(context, snapshot.error);
+          return widget.errorWidgetBuilder(context, snapshot.error!);
         } else if (!snapshot.hasData) {
           return widget.loadingBuilder(context);
         } else {
-          final messageList = snapshot.data?.reversed?.toList() ?? [];
+          final messageList =
+              snapshot.data?.reversed.toList(growable: false) ?? [];
           if (messageList.isEmpty && !_isThreadConversation) {
             if (_upToDate) {
               return widget.emptyBuilder(context);
@@ -169,13 +162,14 @@ class MessageListCoreState extends State<MessageListCore> {
 
   /// Fetches more messages with updated pagination and updates the widget.
   ///
-  /// Optionally pass the fetch direction, defaults to [QueryDirection.bottom]
+  /// Optionally pass the fetch direction, defaults to [QueryDirection.top]
-  Future<void> paginateData(
+  Future<void> paginateData({
-      {QueryDirection direction = QueryDirection.bottom}) {
+    QueryDirection direction = QueryDirection.top,
+  }) {
     if (!_isThreadConversation) {
       return _streamChannel.queryMessages(direction: direction);
     } else {
-      return _streamChannel.getReplies(widget.parentMessage.id);
+      return _streamChannel.getReplies(widget.parentMessage!.id);
     }
   }
 
@@ -184,11 +178,11 @@ class MessageListCoreState extends State<MessageListCore> {
     _streamChannel = StreamChannel.of(context);
 
     if (_isThreadConversation) {
-      _streamChannel.getReplies(widget.parentMessage.id);
+      _streamChannel.getReplies(widget.parentMessage!.id);
     }
 
     if (widget.messageListController != null) {
-      widget.messageListController.paginateData = paginateData;
+      widget.messageListController!.paginateData = paginateData;
     }
 
     super.initState();
@@ -206,5 +200,5 @@ class MessageListCoreState extends State<MessageListCore> {
 /// Controller used for paginating data in [ChannelListView]
 class MessageListController {
   /// Call this function to load further data
-  Future<void> Function({QueryDirection direction}) paginateData;
+  Future<void> Function({QueryDirection direction})? paginateData;
 }

packages/stream_chat_flutter_core/lib/src/message_search_bloc.dart

@@ -13,10 +13,9 @@ import 'package:stream_chat_flutter_core/src/stream_chat_core.dart';
 class MessageSearchBloc extends StatefulWidget {
   /// Instantiate a new MessageSearchBloc
   const MessageSearchBloc({
-    Key key,
+    Key? key,
-    @required this.child,
+    required this.child,
-  })  : assert(child != null, 'Parameter child should not be null.'),
+  }) : super(key: key);
-        super(key: key);
 
   /// The widget child
   final Widget child;
@@ -26,7 +25,7 @@ class MessageSearchBloc extends StatefulWidget {
 
   /// Use this method to get the current [MessageSearchBlocState] instance
   static MessageSearchBlocState of(BuildContext context) {
-    MessageSearchBlocState state;
+    MessageSearchBlocState? state;
 
     state = context.findAncestorStateOfType<MessageSearchBlocState>();
 
@@ -42,7 +41,7 @@ class MessageSearchBloc extends StatefulWidget {
 class MessageSearchBlocState extends State<MessageSearchBloc>
     with AutomaticKeepAliveClientMixin {
   /// The current messages list
-  List<GetMessageResponse> get messageResponses => _messageResponses.value;
+  List<GetMessageResponse>? get messageResponses => _messageResponses.value;
 
   /// The current messages list as a stream
   Stream<List<GetMessageResponse>> get messagesStream =>
@@ -59,11 +58,11 @@ class MessageSearchBlocState extends State<MessageSearchBloc>
   /// Calls [StreamChatClient.search] updating
   /// [messagesStream] and [queryMessagesLoading] stream
   Future<void> search({
-    Map<String, dynamic> filter,
+    required Map<String, dynamic> filter,
-    Map<String, dynamic> messageFilter,
+    Map<String, dynamic>? messageFilter,
-    List<SortOption> sort,
+    List<SortOption>? sort,
-    String query,
+    String? query,
-    PaginationParams pagination,
+    PaginationParams? pagination,
   }) async {
     final client = StreamChatCore.of(context).client;
 
@@ -73,9 +72,7 @@ class MessageSearchBlocState extends State<MessageSearchBloc>
       _queryMessagesLoadingController.add(true);
     }
     try {
-      final clear = pagination == null ||
+      final clear = pagination == null || pagination.offset == 0;
-          pagination.offset == null ||
-          pagination.offset == 0;
 
       final oldMessages = List<GetMessageResponse>.from(messageResponses ?? []);
 
@@ -93,7 +90,8 @@ class MessageSearchBlocState extends State<MessageSearchBloc>
         final temp = oldMessages + messages.results;
         _messageResponses.add(temp);
       }
-      if (_messageResponses.hasValue && _queryMessagesLoadingController.value) {
+      if (_messageResponses.hasValue &&
+          _queryMessagesLoadingController.value!) {
         _queryMessagesLoadingController.add(false);
       }
     } catch (e, stk) {

packages/stream_chat_flutter_core/lib/src/message_search_list_core.dart

@@ -42,31 +42,27 @@ class MessageSearchListCore extends StatefulWidget {
   /// * [loadingBuilder]
   /// * [childBuilder]
   const MessageSearchListCore({
-    Key key,
+    Key? key,
-    @required this.emptyBuilder,
+    required this.emptyBuilder,
-    @required this.errorBuilder,
+    required this.errorBuilder,
-    @required this.loadingBuilder,
+    required this.loadingBuilder,
-    @required this.childBuilder,
+    required this.childBuilder,
+    required this.filters,
     this.messageQuery,
-    this.filters,
     this.sortOptions,
     this.paginationParams,
     this.messageFilters,
     this.messageSearchListController,
-  })  : assert(emptyBuilder != null, 'emptyBuilder should not be null'),
+  }) : super(key: key);
-        assert(errorBuilder != null, 'errorBuilder should not be null'),
-        assert(loadingBuilder != null, 'loadingBuilder should not be null'),
-        assert(childBuilder != null, 'childBuilder should not be null'),
-        super(key: key);
 
   /// A [MessageSearchListController] allows reloading and pagination.
   /// Use [MessageSearchListController.loadData] and
   /// [MessageSearchListController.paginateData] respectively for reloading and
   /// pagination.
-  final MessageSearchListController messageSearchListController;
+  final MessageSearchListController? messageSearchListController;
 
   /// Message String to search on
-  final String messageQuery;
+  final String? messageQuery;
 
   /// The query filters to use.
   /// You can query on any of the custom fields you've defined on the [Channel].
@@ -78,18 +74,18 @@ class MessageSearchListCore extends StatefulWidget {
   /// provided.
   /// You can sort based on last_updated, last_message_at, updated_at, created_
   /// at or member_count. Direction can be ascending or descending.
-  final List<SortOption> sortOptions;
+  final List<SortOption>? sortOptions;
 
   /// Pagination parameters
   /// limit: the number of users to return (max is 30)
   /// offset: the offset (max is 1000)
   /// message_limit: how many messages should be included to each channel
-  final PaginationParams paginationParams;
+  final PaginationParams? paginationParams;
 
   /// The message query filters to use.
   /// You can query on any of the custom fields you've defined on the [Channel].
   /// You can also filter other built-in channel fields.
-  final Map<String, dynamic> messageFilters;
+  final Map<String, dynamic>? messageFilters;
 
   /// The builder that is used when the search messages are fetched
   final Widget Function(List<GetMessageResponse>) childBuilder;
@@ -114,8 +110,8 @@ class MessageSearchListCoreState extends State<MessageSearchListCore> {
     super.didChangeDependencies();
     loadData();
     if (widget.messageSearchListController != null) {
-      widget.messageSearchListController.loadData = loadData;
+      widget.messageSearchListController!.loadData = loadData;
-      widget.messageSearchListController.paginateData = paginateData;
+      widget.messageSearchListController!.paginateData = paginateData;
     }
   }
 
@@ -130,16 +126,16 @@ class MessageSearchListCoreState extends State<MessageSearchListCore> {
         stream: messageSearchBloc.messagesStream,
         builder: (context, snapshot) {
           if (snapshot.hasError) {
-            return widget.errorBuilder(context, snapshot.error);
+            return widget.errorBuilder(context, snapshot.error!);
           }
           if (!snapshot.hasData) {
             return widget.loadingBuilder(context);
           }
-          final items = snapshot.data;
+          final items = snapshot.data!;
           if (items.isEmpty) {
             return widget.emptyBuilder(context);
           }
-          return widget.childBuilder(snapshot.data);
+          return widget.childBuilder(items);
         },
       );
 
@@ -161,7 +157,7 @@ class MessageSearchListCoreState extends State<MessageSearchListCore> {
     return messageSearchBloc.search(
       filter: widget.filters,
       sort: widget.sortOptions,
-      pagination: widget.paginationParams.copyWith(
+      pagination: widget.paginationParams!.copyWith(
         offset: messageSearchBloc.messageResponses?.length ?? 0,
       ),
       query: widget.messageQuery,
@@ -172,13 +168,13 @@ class MessageSearchListCoreState extends State<MessageSearchListCore> {
   @override
   void didUpdateWidget(MessageSearchListCore oldWidget) {
     super.didUpdateWidget(oldWidget);
-    if (widget.filters?.toString() != oldWidget.filters?.toString() ||
+    if (widget.filters.toString() != oldWidget.filters.toString() ||
         jsonEncode(widget.sortOptions) != jsonEncode(oldWidget.sortOptions) ||
         widget.messageQuery?.toString() != oldWidget.messageQuery?.toString() ||
         widget.messageFilters?.toString() !=
             oldWidget.messageFilters?.toString() ||
-        widget.paginationParams?.toJson()?.toString() !=
+        widget.paginationParams?.toJson().toString() !=
-            oldWidget.paginationParams?.toJson()?.toString()) {
+            oldWidget.paginationParams?.toJson().toString()) {
       loadData();
     }
   }
@@ -187,8 +183,8 @@ class MessageSearchListCoreState extends State<MessageSearchListCore> {
 /// Controller used for paginating data in [ChannelListView]
 class MessageSearchListController {
   /// Call this function to reload data
-  AsyncCallback loadData;
+  AsyncCallback? loadData;
 
   /// Call this function to load further data
-  AsyncCallback paginateData;
+  AsyncCallback? paginateData;
 }

packages/stream_chat_flutter_core/lib/src/stream_channel.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 
+import 'package:collection/collection.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:rxdart/rxdart.dart';
@@ -21,16 +22,14 @@ class StreamChannel extends StatefulWidget {
   /// Creates a new instance of [StreamChannel]. Both [child] and [client] must
   /// be supplied and not null.
   const StreamChannel({
-    Key key,
+    Key? key,
-    @required this.child,
+    required this.child,
-    @required this.channel,
+    required this.channel,
     this.showLoading = true,
     this.initialMessageId,
-  })  : assert(child != null, 'Child should not be null'),
+  }) : super(key: key);
-        assert(channel != null, 'Channel should not be null'),
-        super(key: key);
 
-  // ignore: public_member_api_docs
+  /// The child of the widget
   final Widget child;
 
   /// [channel] specifies the channel with which child should be wrapped
@@ -40,11 +39,11 @@ class StreamChannel extends StatefulWidget {
   final bool showLoading;
 
   /// If passed the channel will load from this particular message.
-  final String initialMessageId;
+  final String? initialMessageId;
 
   /// Use this method to get the current [StreamChannelState] instance
   static StreamChannelState of(BuildContext context) {
-    StreamChannelState streamChannelState;
+    StreamChannelState? streamChannelState;
 
     streamChannelState = context.findAncestorStateOfType<StreamChannelState>();
 
@@ -67,11 +66,11 @@ class StreamChannelState extends State<StreamChannel> {
   Channel get channel => widget.channel;
 
   /// InitialMessageId
-  String get initialMessageId => widget.initialMessageId;
+  String? get initialMessageId => widget.initialMessageId;
 
   /// Current channel state stream
-  Stream<ChannelState> get channelStateStream =>
+  Stream<ChannelState>? get channelStateStream =>
-      widget.channel.state.channelStateStream;
+      widget.channel.state?.channelStateStream;
 
   final _queryTopMessagesController = BehaviorSubject.seeded(false);
   final _queryBottomMessagesController = BehaviorSubject.seeded(false);
@@ -89,16 +88,18 @@ class StreamChannelState extends State<StreamChannel> {
     int limit = 20,
     bool preferOffline = false,
   }) async {
-    if (_topPaginationEnded || _queryTopMessagesController?.value == true) {
+    if (_topPaginationEnded ||
+        _queryTopMessagesController.value == true ||
+        channel.state == null) {
       return;
     }
     _queryTopMessagesController.add(true);
 
-    if (channel.state.messages.isEmpty) {
+    if (channel.state!.messages.isEmpty) {
       return _queryTopMessagesController.add(false);
     }
 
-    final oldestMessage = channel.state.messages.first;
+    final oldestMessage = channel.state!.messages.first;
 
     try {
       final state = await queryBeforeMessage(
@@ -120,15 +121,16 @@ class StreamChannelState extends State<StreamChannel> {
     bool preferOffline = false,
   }) async {
     if (_bottomPaginationEnded ||
-        _queryBottomMessagesController?.value == true ||
+        _queryBottomMessagesController.value == true ||
-        channel?.state?.isUpToDate == true) return;
+        channel.state == null ||
+        channel.state!.isUpToDate == true) return;
     _queryBottomMessagesController.add(true);
 
-    if (channel.state.messages.isEmpty) {
+    if (channel.state!.messages.isEmpty) {
       return _queryBottomMessagesController.add(false);
     }
 
-    final recentMessage = channel.state.messages.last;
+    final recentMessage = channel.state!.messages.last;
 
     try {
       final state = await queryAfterMessage(
@@ -146,7 +148,7 @@ class StreamChannelState extends State<StreamChannel> {
   }
 
   /// Calls [channel.query] updating [queryMessage] stream
-  Future<void> queryMessages({QueryDirection direction = QueryDirection.top}) {
+  Future<void> queryMessages({QueryDirection? direction = QueryDirection.top}) {
     if (direction == QueryDirection.top) return _queryTopMessages();
     return _queryBottomMessages();
   }
@@ -157,12 +159,14 @@ class StreamChannelState extends State<StreamChannel> {
     int limit = 50,
     bool preferOffline = false,
   }) async {
-    if (_topPaginationEnded || _queryTopMessagesController.value) return;
+    if (_topPaginationEnded ||
+        _queryTopMessagesController.value! ||
+        channel.state == null) return;
     _queryTopMessagesController.add(true);
 
-    Message message;
+    late Message message;
-    if (channel.state.threads.containsKey(parentId)) {
+    if (channel.state!.threads.containsKey(parentId)) {
-      final thread = channel.state.threads[parentId];
+      final thread = channel.state!.threads[parentId]!;
       if (thread.isNotEmpty) {
         message = thread.first;
       }
@@ -172,7 +176,7 @@ class StreamChannelState extends State<StreamChannel> {
       final response = await channel.getReplies(
         parentId,
         PaginationParams(
-          lessThan: message?.id,
+          lessThan: message.id,
           limit: limit,
         ),
         preferOffline: preferOffline,
@@ -188,21 +192,26 @@ class StreamChannelState extends State<StreamChannel> {
 
   /// Query the channel members and watchers
   Future<void> queryMembersAndWatchers() async {
-    await widget.channel.query(
+    final _members = channel.state?.members;
-      membersPagination: PaginationParams(
+    if (_members != null) {
-        offset: channel.state.members?.length,
+      await widget.channel.query(
-        limit: 100,
+        membersPagination: PaginationParams(
-      ),
+          offset: _members.length,
-      watchersPagination: PaginationParams(
+          limit: 100,
-        offset: channel.state.watchers?.length,
+        ),
-        limit: 100,
+        watchersPagination: PaginationParams(
-      ),
+          offset: _members.length,
-    );
+          limit: 100,
+        ),
+      );
+    } else {
+      return;
+    }
   }
 
   /// Loads channel at specific message
   Future<void> loadChannelAtMessage(
-    String messageId, {
+    String? messageId, {
     int before = 20,
     int after = 20,
     bool preferOffline = false,
@@ -214,15 +223,15 @@ class StreamChannelState extends State<StreamChannel> {
         preferOffline: preferOffline,
       );
 
-  Future<void> _queryAtMessage({
+  Future<List<ChannelState>> _queryAtMessage({
-    String messageId,
+    String? messageId,
     int before = 20,
     int after = 20,
     bool preferOffline = false,
   }) async {
-    if (channel.state == null) return;
+    if (channel.state == null) return [];
-    channel.state.isUpToDate = false;
+    channel.state!.isUpToDate = false;
-    channel.state.truncate();
+    channel.state!.truncate();
 
     if (messageId == null) {
       await channel.query(
@@ -231,8 +240,8 @@ class StreamChannelState extends State<StreamChannel> {
         ),
         preferOffline: preferOffline,
       );
-      channel.state.isUpToDate = true;
+      channel.state!.isUpToDate = true;
-      return;
+      return [];
     }
 
     return Future.wait([
@@ -277,16 +286,15 @@ class StreamChannelState extends State<StreamChannel> {
       preferOffline: preferOffline,
     );
     if (state.messages.isEmpty || state.messages.length < limit) {
-      channel.state.isUpToDate = true;
+      channel.state?.isUpToDate = true;
     }
     return state;
   }
 
   ///
   Future<Message> getMessage(String messageId) async {
-    var message = channel.state.messages.firstWhere(
+    var message = channel.state?.messages.firstWhereOrNull(
       (it) => it.id == messageId,
-      orElse: () => null,
     );
     if (message == null) {
       final response = await channel.getMessagesById([messageId]);
@@ -298,7 +306,7 @@ class StreamChannelState extends State<StreamChannel> {
   /// Reloads the channel with latest message
   Future<void> reloadChannel() => _queryAtMessage(before: 30);
 
-  List<Future<bool>> _futures;
+  late List<Future<bool>> _futures;
 
   Future<bool> get _loadChannelAtMessage async {
     try {
@@ -358,9 +366,9 @@ class StreamChannelState extends State<StreamChannel> {
           }
           return Center(child: Text(message));
         }
-        final initialized = snapshot.data[0];
+        final initialized = snapshot.data![0];
         // ignore: avoid_bool_literals_in_conditional_expressions
-        final dataLoaded = initialMessageId == null ? true : snapshot.data[1];
+        final dataLoaded = initialMessageId == null ? true : snapshot.data![1];
         if (widget.showLoading && (!initialized || !dataLoaded)) {
           return const Center(
             child: CircularProgressIndicator(),

packages/stream_chat_flutter_core/lib/src/stream_chat_core.dart

@@ -38,14 +38,12 @@ class StreamChatCore extends StatefulWidget {
   /// [StreamChatCore] is a stateful widget which reacts to system events and
   /// updates Stream's connection status accordingly.
   const StreamChatCore({
-    Key key,
+    Key? key,
-    @required this.client,
+    required this.client,
-    @required this.child,
+    required this.child,
     this.onBackgroundEventReceived,
     this.backgroundKeepAlive = const Duration(minutes: 1),
-  })  : assert(client != null, 'Stream Chat Client should not be null'),
+  }) : super(key: key);
-        assert(child != null, 'Child should not be null'),
-        super(key: key);
 
   /// Instance of Stream Chat Client containing information about the current
   /// application.
@@ -61,14 +59,14 @@ class StreamChatCore extends StatefulWidget {
   /// Handler called whenever the [client] receives a new [Event] while the app
   /// is in background. Can be used to display various notifications depending
   /// upon the [Event.type]
-  final EventHandler onBackgroundEventReceived;
+  final EventHandler? onBackgroundEventReceived;
 
   @override
   StreamChatCoreState createState() => StreamChatCoreState();
 
   /// Use this method to get the current [StreamChatCoreState] instance
   static StreamChatCoreState of(BuildContext context) {
-    StreamChatCoreState streamChatState;
+    StreamChatCoreState? streamChatState;
 
     streamChatState = context.findAncestorStateOfType<StreamChatCoreState>();
 
@@ -87,24 +85,24 @@ class StreamChatCoreState extends State<StreamChatCore>
   /// Initialized client used throughout the application.
   StreamChatClient get client => widget.client;
 
-  Timer _disconnectTimer;
+  Timer? _disconnectTimer;
 
   @override
   Widget build(BuildContext context) => widget.child;
 
   /// The current user
-  User get user => client.state?.user;
+  User? get user => client.state.user;
 
   /// The current user as a stream
-  Stream<User> get userStream => client.state?.userStream;
+  Stream<User?> get userStream => client.state.userStream;
 
   @override
   void initState() {
     super.initState();
-    WidgetsBinding.instance.addObserver(this);
+    WidgetsBinding.instance?.addObserver(this);
   }
 
-  StreamSubscription _eventSubscription;
+  StreamSubscription? _eventSubscription;
 
   @override
   void didChangeAppLifecycleState(AppLifecycleState state) {
@@ -119,15 +117,15 @@ class StreamChatCoreState extends State<StreamChatCore>
             );
 
         void onTimerComplete() {
-          _eventSubscription.cancel();
+          _eventSubscription?.cancel();
           client.disconnect();
         }
 
         _disconnectTimer = Timer(widget.backgroundKeepAlive, onTimerComplete);
       } else if (state == AppLifecycleState.resumed) {
         if (_disconnectTimer?.isActive == true) {
-          _eventSubscription.cancel();
+          _eventSubscription?.cancel();
-          _disconnectTimer.cancel();
+          _disconnectTimer?.cancel();
         } else {
           if (client.wsConnectionStatus == ConnectionStatus.disconnected) {
             client.connect();
@@ -139,7 +137,7 @@ class StreamChatCoreState extends State<StreamChatCore>
 
   @override
   void dispose() {
-    WidgetsBinding.instance.removeObserver(this);
+    WidgetsBinding.instance?.removeObserver(this);
     _eventSubscription?.cancel();
     _disconnectTimer?.cancel();
     super.dispose();

packages/stream_chat_flutter_core/lib/src/user_list_core.dart

@@ -57,27 +57,23 @@ import 'package:stream_chat_flutter_core/src/users_bloc.dart';
 class UserListCore extends StatefulWidget {
   /// Instantiate a new [UserListCore]
   const UserListCore({
-    @required this.errorBuilder,
+    required this.errorBuilder,
-    @required this.emptyBuilder,
+    required this.emptyBuilder,
-    @required this.loadingBuilder,
+    required this.loadingBuilder,
-    @required this.listBuilder,
+    required this.listBuilder,
-    Key key,
+    Key? key,
     this.filter,
     this.options,
     this.sort,
     this.pagination,
     this.groupAlphabetically = false,
     this.userListController,
-  })  : assert(errorBuilder != null, ''),
+  }) : super(key: key);
-        assert(emptyBuilder != null, ''),
-        assert(loadingBuilder != null, ''),
-        assert(listBuilder != null, ''),
-        super(key: key);
 
   /// A [UserListController] allows reloading and pagination.
   /// Use [UserListController.loadData] and [UserListController.paginateData]
   /// respectively for reloading and pagination.
-  final UserListController userListController;
+  final UserListController? userListController;
 
   /// The builder that will be used in case of error
   final Widget Function(Object error) errorBuilder;
@@ -94,25 +90,25 @@ class UserListCore extends StatefulWidget {
   /// The query filters to use.
   /// You can query on any of the custom fields you've defined on the [Channel].
   /// You can also filter other built-in channel fields.
-  final Map<String, dynamic> filter;
+  final Map<String, dynamic>? filter;
 
   /// Query channels options.
   ///
   /// state: if true returns the Channel state
   /// watch: if true listen to changes to this Channel in real time.
-  final Map<String, dynamic> options;
+  final Map<String, dynamic>? options;
 
   /// The sorting used for the channels matching the filters.
   /// Sorting is based on field and direction, multiple sorting options can be
   /// provided. You can sort based on last_updated, last_message_at, updated_at,
   /// created_at or member_count. Direction can be ascending or descending.
-  final List<SortOption> sort;
+  final List<SortOption>? sort;
 
   /// Pagination parameters
   /// limit: the number of users to return (max is 30)
   /// offset: the offset (max is 1000)
   /// message_limit: how many messages should be included to each channel
-  final PaginationParams pagination;
+  final PaginationParams? pagination;
 
   /// Set it to true to group users by their first character
   ///
@@ -131,8 +127,8 @@ class UserListCoreState extends State<UserListCore>
     super.didChangeDependencies();
     loadData();
     if (widget.userListController != null) {
-      widget.userListController.loadData = loadData;
+      widget.userListController!.loadData = loadData;
-      widget.userListController.paginateData = paginateData;
+      widget.userListController!.paginateData = paginateData;
     }
   }
 
@@ -158,14 +154,14 @@ class UserListCoreState extends State<UserListCore>
             }
             final groupedUsers = <String, List<User>>{};
             for (final e in temp) {
-              final alphabet = e.name[0]?.toUpperCase();
+              final alphabet = e.name[0].toUpperCase();
               groupedUsers[alphabet] = [...groupedUsers[alphabet] ?? [], e];
             }
             final items = <ListItem>[];
             for (final key in groupedUsers.keys) {
               items
                 ..add(ListHeaderItem(key))
-                ..addAll(groupedUsers[key].map((e) => ListUserItem(e)));
+                ..addAll(groupedUsers[key]!.map((e) => ListUserItem(e)));
             }
             return items;
           }
@@ -180,12 +176,12 @@ class UserListCoreState extends State<UserListCore>
         stream: _buildUserStream(usersBlocState),
         builder: (context, snapshot) {
           if (snapshot.hasError) {
-            return widget.errorBuilder(snapshot.error);
+            return widget.errorBuilder(snapshot.error!);
           }
           if (!snapshot.hasData) {
             return widget.loadingBuilder(context);
           }
-          final items = snapshot.data;
+          final items = snapshot.data!;
           if (items.isEmpty) {
             return widget.emptyBuilder(context);
           }
@@ -210,7 +206,7 @@ class UserListCoreState extends State<UserListCore>
     return _usersBloc.queryUsers(
       filter: widget.filter,
       sort: widget.sort,
-      pagination: widget.pagination.copyWith(
+      pagination: widget.pagination!.copyWith(
         offset: _usersBloc.users?.length ?? 0,
       ),
       options: widget.options,
@@ -223,8 +219,8 @@ class UserListCoreState extends State<UserListCore>
     if (widget.filter?.toString() != oldWidget.filter?.toString() ||
         jsonEncode(widget.sort) != jsonEncode(oldWidget.sort) ||
         widget.options?.toString() != oldWidget.options?.toString() ||
-        widget.pagination?.toJson()?.toString() !=
+        widget.pagination?.toJson().toString() !=
-            oldWidget.pagination?.toJson()?.toString()) {
+            oldWidget.pagination?.toJson().toString()) {
       loadData();
     }
   }
@@ -235,7 +231,7 @@ class UserListCoreState extends State<UserListCore>
 /// with `USER`.
 abstract class ListItem {
   /// Unique key per list item
-  String get key {
+  String? get key {
     if (this is ListHeaderItem) {
       final header = (this as ListHeaderItem).heading;
       return 'HEADER-${header.toLowerCase()}';
@@ -250,8 +246,8 @@ abstract class ListItem {
   /// Helper function to build widget based on ListItem type
   // ignore: missing_return
   Widget when({
-    @required Widget Function(String heading) headerItem,
+    required Widget Function(String heading) headerItem,
-    @required Widget Function(User user) userItem,
+    required Widget Function(User user) userItem,
   }) {
     if (this is ListHeaderItem) {
       return headerItem((this as ListHeaderItem).heading);
@@ -259,6 +255,7 @@ abstract class ListItem {
     if (this is ListUserItem) {
       return userItem((this as ListUserItem).user);
     }
+    return Container();
   }
 }
 
@@ -283,8 +280,8 @@ class ListUserItem extends ListItem {
 /// Controller used for paginating data in [ChannelListView]
 class UserListController {
   /// Call this function to reload data
-  AsyncCallback loadData;
+  AsyncCallback? loadData;
 
   /// Call this function to load further data
-  AsyncCallback paginateData;
+  AsyncCallback? paginateData;
 }

packages/stream_chat_flutter_core/lib/src/users_bloc.dart

@@ -14,13 +14,9 @@ class UsersBloc extends StatefulWidget {
   /// Instantiate a new [UsersBloc]. The parameter [child] must be supplied and
   /// not null.
   const UsersBloc({
-    @required this.child,
+    required this.child,
-    Key key,
+    Key? key,
-  })  : assert(
+  }) : super(key: key);
-            child != null,
-            'When constructing a UsersBloc, the parameter '
-            'child should not be null.'),
-        super(key: key);
 
   /// The widget child
   final Widget child;
@@ -30,7 +26,7 @@ class UsersBloc extends StatefulWidget {
 
   /// Use this method to get the current [UsersBlocState] instance
   static UsersBlocState of(BuildContext context) {
-    UsersBlocState state;
+    UsersBlocState? state;
 
     state = context.findAncestorStateOfType<UsersBlocState>();
 
@@ -46,7 +42,7 @@ class UsersBloc extends StatefulWidget {
 class UsersBlocState extends State<UsersBloc>
     with AutomaticKeepAliveClientMixin {
   /// The current users list
-  List<User> get users => _usersController.value;
+  List<User>? get users => _usersController.value;
 
   /// The current users list as a stream
   Stream<List<User>> get usersStream => _usersController.stream;
@@ -62,10 +58,10 @@ class UsersBlocState extends State<UsersBloc>
   /// online/offline.
   /// [API Reference](https://getstream.io/chat/docs/flutter-dart/query_users/?language=dart)
   Future<void> queryUsers({
-    Map<String, dynamic> filter,
+    Map<String, dynamic>? filter,
-    List<SortOption> sort,
+    List<SortOption>? sort,
-    Map<String, dynamic> options,
+    Map<String, dynamic>? options,
-    PaginationParams pagination,
+    PaginationParams? pagination,
   }) async {
     final client = StreamChatCore.of(context).client;
 
@@ -76,9 +72,7 @@ class UsersBlocState extends State<UsersBloc>
     }
 
     try {
-      final clear = pagination == null ||
+      final clear = pagination == null || pagination.offset == 0;
-          pagination.offset == null ||
-          pagination.offset == 0;
 
       final oldUsers = List<User>.from(users ?? []);
 
@@ -95,7 +89,7 @@ class UsersBlocState extends State<UsersBloc>
         final temp = oldUsers + usersResponse.users;
         _usersController.add(temp);
       }
-      if (_usersController.hasValue && _queryUsersLoadingController.value) {
+      if (_usersController.hasValue && _queryUsersLoadingController.value!) {
         _queryUsersLoadingController.add(false);
       }
     } catch (e, stk) {

packages/stream_chat_flutter_core/pubspec.yaml

@@ -8,23 +8,24 @@ issue_tracker: https://github.com/GetStream/stream-chat-flutter/issues
 publish_to: none
 
 environment:
-  sdk: ">=2.7.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
   flutter: ">=1.17.0"
 
 dependencies:
+  collection: ^1.15.0-nullsafety.4
   flutter:
     sdk: flutter
-  meta: ^1.2.4
+  meta: ^1.3.0
   rxdart: ^0.26.0
-  stream_chat: ^1.5.0
+  stream_chat: ^1.5.2
 
 dependency_overrides:
   stream_chat:
     path: ../stream_chat
 
 dev_dependencies:
-  fake_async: ^1.1.0
+  fake_async: ^1.2.0
   flutter_test:
     sdk: flutter
-  mockito: ^4.1.3
+  mocktail: ^0.1.1
 

packages/stream_chat_flutter_core/test/channel_list_core_test.dart

@@ -1,8 +1,8 @@
 import 'dart:async';
 
-import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/widgets.dart';
-import 'package:mockito/mockito.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:mocktail/mocktail.dart';
 import 'package:stream_chat_flutter_core/src/channel_list_core.dart';
 import 'package:stream_chat_flutter_core/stream_chat_flutter_core.dart';
 
@@ -30,58 +30,6 @@ void main() {
     );
   }
 
-  test(
-    'should throw assertion error in case listBuilder is null',
-    () {
-      final channelListCore = () => ChannelListCore(
-            listBuilder: null,
-            loadingBuilder: (BuildContext context) => Offstage(),
-            emptyBuilder: (BuildContext context) => Offstage(),
-            errorBuilder: (BuildContext context, Object error) => Offstage(),
-          );
-      expect(channelListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error in case loadingBuilder is null',
-    () {
-      final channelListCore = () => ChannelListCore(
-            listBuilder: (_, __) => Offstage(),
-            loadingBuilder: null,
-            emptyBuilder: (BuildContext context) => Offstage(),
-            errorBuilder: (BuildContext context, Object error) => Offstage(),
-          );
-      expect(channelListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error in case emptyBuilder is null',
-    () {
-      final channelListCore = () => ChannelListCore(
-            listBuilder: (_, __) => Offstage(),
-            loadingBuilder: (BuildContext context) => Offstage(),
-            emptyBuilder: null,
-            errorBuilder: (BuildContext context, Object error) => Offstage(),
-          );
-      expect(channelListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error in case errorBuilder is null',
-    () {
-      final channelListCore = () => ChannelListCore(
-            listBuilder: (_, __) => Offstage(),
-            loadingBuilder: (BuildContext context) => Offstage(),
-            emptyBuilder: (BuildContext context) => Offstage(),
-            errorBuilder: null,
-          );
-      expect(channelListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
   testWidgets(
     'should throw if ChannelListCore is used where ChannelsBloc is not present '
     'in the widget tree',
@@ -116,7 +64,8 @@ void main() {
 
       final mockClient = MockClient();
 
-      when(mockClient.on(any, any, any, any)).thenAnswer((_) => Stream.empty());
+      when(() => mockClient.on(any(), any(), any(), any()))
+          .thenAnswer((_) => Stream.empty());
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -151,7 +100,8 @@ void main() {
 
       final mockClient = MockClient();
 
-      when(mockClient.on(any, any, any, any)).thenAnswer((_) => Stream.empty());
+      when(() => mockClient.on(any(), any(), any(), any()))
+          .thenAnswer((_) => Stream.empty());
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -185,15 +135,16 @@ void main() {
 
       final mockClient = MockClient();
 
-      when(mockClient.on(any, any, any, any)).thenAnswer((_) => Stream.empty());
+      when(() => mockClient.on(any(), any(), any(), any()))
+          .thenAnswer((_) => Stream.empty());
 
       const error = 'Error! Error! Error!';
-      when(mockClient.queryChannels(
+      when(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).thenThrow(error);
+          )).thenThrow(error);
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -208,12 +159,12 @@ void main() {
 
       expect(find.byKey(errorWidgetKey), findsOneWidget);
 
-      verify(mockClient.queryChannels(
+      verify(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -233,15 +184,16 @@ void main() {
 
       final mockClient = MockClient();
 
-      when(mockClient.on(any, any, any, any)).thenAnswer((_) => Stream.empty());
+      when(() => mockClient.on(any(), any(), any(), any()))
+          .thenAnswer((_) => Stream.empty());
 
       const channels = <Channel>[];
-      when(mockClient.queryChannels(
+      when(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).thenAnswer((_) => Stream.value(channels));
+          )).thenAnswer((_) => Stream.value(channels));
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -256,12 +208,12 @@ void main() {
 
       expect(find.byKey(emptyWidgetKey), findsOneWidget);
 
-      verify(mockClient.queryChannels(
+      verify(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -281,15 +233,16 @@ void main() {
 
       final mockClient = MockClient();
 
-      when(mockClient.on(any, any, any, any)).thenAnswer((_) => Stream.empty());
+      when(() => mockClient.on(any(), any(), any(), any()))
+          .thenAnswer((_) => Stream.empty());
 
       final channels = _generateChannels(mockClient);
-      when(mockClient.queryChannels(
+      when(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).thenAnswer((_) => Stream.value(channels));
+          )).thenAnswer((_) => Stream.value(channels));
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -304,12 +257,12 @@ void main() {
 
       expect(find.byKey(listWidgetKey), findsOneWidget);
 
-      verify(mockClient.queryChannels(
+      verify(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -337,15 +290,16 @@ void main() {
 
       final mockClient = MockClient();
 
-      when(mockClient.on(any, any, any, any)).thenAnswer((_) => Stream.empty());
+      when(() => mockClient.on(any(), any(), any(), any()))
+          .thenAnswer((_) => Stream.empty());
 
       final channels = _generateChannels(mockClient);
-      when(mockClient.queryChannels(
+      when(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).thenAnswer((_) => Stream.value(channels));
+          )).thenAnswer((_) => Stream.value(channels));
 
       await tester.pumpWidget(
         Directionality(
@@ -364,12 +318,12 @@ void main() {
       expect(find.byKey(listWidgetKey), findsOneWidget);
       expect(find.text(channels.map((e) => e.cid).join(',')), findsOneWidget);
 
-      verify(mockClient.queryChannels(
+      verify(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).called(1);
+          )).called(1);
 
       final channelListCoreState = tester.state<ChannelListCoreState>(
         find.byKey(channelListCoreKey),
@@ -378,12 +332,12 @@ void main() {
       final offset = channels.length;
       final paginatedChannels = _generateChannels(mockClient, offset: offset);
       final updatedPagination = pagination.copyWith(offset: offset);
-      when(mockClient.queryChannels(
+      when(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: updatedPagination,
+            paginationParams: updatedPagination,
-      )).thenAnswer((_) => Stream.value(paginatedChannels));
+          )).thenAnswer((_) => Stream.value(paginatedChannels));
 
       await channelListCoreState.paginateData();
 
@@ -398,12 +352,12 @@ void main() {
         findsOneWidget,
       );
 
-      verify(mockClient.queryChannels(
+      verify(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: updatedPagination,
+            paginationParams: updatedPagination,
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -411,8 +365,8 @@ void main() {
     'should rebuild ChannelListCore with updated widget data '
     'on calling setState()',
     (tester) async {
-      StateSetter _stateSetter;
+      StateSetter? _stateSetter;
-      int limit = pagination.limit;
+      var limit = pagination.limit;
 
       const channelListCoreKey = Key('channelListCore');
       const listWidgetKey = Key('listWidget');
@@ -435,15 +389,16 @@ void main() {
 
       final mockClient = MockClient();
 
-      when(mockClient.on(any, any, any, any)).thenAnswer((_) => Stream.empty());
+      when(() => mockClient.on(any(), any(), any(), any()))
+          .thenAnswer((_) => Stream.empty());
 
       final channels = _generateChannels(mockClient);
-      when(mockClient.queryChannels(
+      when(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).thenAnswer((_) => Stream.value(channels));
+          )).thenAnswer((_) => Stream.value(channels));
 
       await tester.pumpWidget(
         Directionality(
@@ -466,24 +421,24 @@ void main() {
       expect(find.byKey(listWidgetKey), findsOneWidget);
       expect(find.text(channels.map((e) => e.cid).join(',')), findsOneWidget);
 
-      verify(mockClient.queryChannels(
+      verify(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).called(1);
+          )).called(1);
 
       // Rebuilding ChannelListCore with new pagination limit
-      _stateSetter(() => limit = 6);
+      _stateSetter?.call(() => limit = 6);
 
       final updatedChannels = _generateChannels(mockClient, count: limit);
       final updatedPagination = pagination.copyWith(limit: limit);
-      when(mockClient.queryChannels(
+      when(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: updatedPagination,
+            paginationParams: updatedPagination,
-      )).thenAnswer((_) => Stream.value(updatedChannels));
+          )).thenAnswer((_) => Stream.value(updatedChannels));
 
       await tester.pumpAndSettle();
 
@@ -493,12 +448,12 @@ void main() {
         findsOneWidget,
       );
 
-      verify(mockClient.queryChannels(
+      verify(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: updatedPagination,
+            paginationParams: updatedPagination,
-      )).called(1);
+          )).called(1);
     },
   );
 }

packages/stream_chat_flutter_core/test/channels_bloc_test.dart

@@ -2,13 +2,17 @@ import 'dart:async';
 
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:mockito/mockito.dart';
+import 'package:mocktail/mocktail.dart';
 import 'package:stream_chat_flutter_core/stream_chat_flutter_core.dart';
 
 import 'matchers/channel_matcher.dart';
 import 'mocks.dart';
 
 void main() {
+  setUpAll(() {
+    registerFallbackValue<PaginationParams>(const PaginationParams());
+  });
+
   List<Channel> _generateChannels(
     StreamChatClient client, {
     int count = 3,
@@ -28,18 +32,6 @@ void main() {
     );
   }
 
-  test(
-    'should throw assertion error if child is null',
-    () async {
-      const channelsBlocKey = Key('channelsBloc');
-      final channelsBloc = () => ChannelsBloc(
-            key: channelsBlocKey,
-            child: null,
-          );
-      expect(channelsBloc, throwsA(isA<AssertionError>()));
-    },
-  );
-
   testWidgets(
     'should throw if ChannelsBloc is used where StreamChat is not present in the widget tree',
     (tester) async {
@@ -70,7 +62,8 @@ void main() {
 
       final mockClient = MockClient();
 
-      when(mockClient.on(any, any, any, any)).thenAnswer((_) => Stream.empty());
+      when(() => mockClient.on(any(), any(), any(), any()))
+          .thenAnswer((_) => Stream.empty());
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -101,7 +94,8 @@ void main() {
 
       final mockClient = MockClient();
 
-      when(mockClient.on(any, any, any, any)).thenAnswer((_) => Stream.empty());
+      when(() => mockClient.on(any(), any(), any(), any()))
+          .thenAnswer((_) => Stream.empty());
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -117,12 +111,12 @@ void main() {
       final offlineChannels = _generateChannels(mockClient);
       final onlineChannels = _generateChannels(mockClient, offset: 3);
 
-      when(mockClient.queryChannels(
+      when(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).thenAnswer(
+          )).thenAnswer(
         (_) => Stream.fromIterable([offlineChannels, onlineChannels]),
       );
 
@@ -136,12 +130,12 @@ void main() {
         ]),
       );
 
-      verify(mockClient.queryChannels(
+      verify(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -163,7 +157,8 @@ void main() {
 
       final mockClient = MockClient();
 
-      when(mockClient.on(any, any, any, any)).thenAnswer((_) => Stream.empty());
+      when(() => mockClient.on(any(), any(), any(), any()))
+          .thenAnswer((_) => Stream.empty());
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -176,14 +171,14 @@ void main() {
         find.byKey(channelsBlocKey),
       );
 
-      final error = 'Error! Error! Error!';
+      const error = 'Error! Error! Error!';
 
-      when(mockClient.queryChannels(
+      when(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).thenThrow(error);
+          )).thenThrow(error);
 
       channelsBlocState.queryChannels();
 
@@ -192,12 +187,12 @@ void main() {
         emitsError(error),
       );
 
-      verify(mockClient.queryChannels(
+      verify(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -214,7 +209,8 @@ void main() {
 
       final mockClient = MockClient();
 
-      when(mockClient.on(any, any, any, any)).thenAnswer((_) => Stream.empty());
+      when(() => mockClient.on(any(), any(), any(), any()))
+          .thenAnswer((_) => Stream.empty());
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -229,38 +225,41 @@ void main() {
 
       final channels = _generateChannels(mockClient);
 
-      when(mockClient.queryChannels(
+      when(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).thenAnswer((_) => Stream.value(channels));
+          )).thenAnswer((_) => Stream.value(channels));
 
-      channelsBlocState.queryChannels();
+      const pagination = PaginationParams(limit: 3);
+      channelsBlocState.queryChannels(
+        paginationParams: pagination,
+      );
 
       await expectLater(
         channelsBlocState.channelsStream,
         emits(isSameChannelListAs(channels)),
       );
 
-      verify(mockClient.queryChannels(
+      verify(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).called(1);
+          )).called(1);
 
       final offset = channels.length;
-      final paginationParams = PaginationParams(offset: offset);
+      final paginationParams = pagination.copyWith(offset: offset);
 
       final newChannels = _generateChannels(mockClient, offset: offset);
 
-      when(mockClient.queryChannels(
+      when(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: paginationParams,
+            paginationParams: paginationParams,
-      )).thenAnswer(
+          )).thenAnswer(
         (_) => Stream.value(newChannels),
       );
 
@@ -277,12 +276,12 @@ void main() {
         ),
       ]);
 
-      verify(mockClient.queryChannels(
+      verify(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: paginationParams,
+            paginationParams: paginationParams,
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -299,7 +298,8 @@ void main() {
 
       final mockClient = MockClient();
 
-      when(mockClient.on(any, any, any, any)).thenAnswer((_) => Stream.empty());
+      when(() => mockClient.on(any(), any(), any(), any()))
+          .thenAnswer((_) => Stream.empty());
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -313,39 +313,41 @@ void main() {
       );
 
       final channels = _generateChannels(mockClient);
+      final paginationParams = const PaginationParams(
+        limit: 3,
+      );
 
-      when(mockClient.queryChannels(
+      when(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: paginationParams,
-      )).thenAnswer((_) => Stream.value(channels));
+          )).thenAnswer((_) => Stream.value(channels));
 
-      channelsBlocState.queryChannels();
+      channelsBlocState.queryChannels(
+        paginationParams: paginationParams,
+      );
 
       await expectLater(
         channelsBlocState.channelsStream,
         emits(isSameChannelListAs(channels)),
       );
 
-      verify(mockClient.queryChannels(
+      verify(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: paginationParams,
-      )).called(1);
+          )).called(1);
-
-      final offset = channels.length;
-      final paginationParams = PaginationParams(offset: offset);
 
       final error = 'Error! Error! Error!';
 
-      when(mockClient.queryChannels(
+      when(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: paginationParams,
+            paginationParams: paginationParams,
-      )).thenThrow(error);
+          )).thenThrow(error);
 
       channelsBlocState.queryChannels(paginationParams: paginationParams);
 
@@ -354,17 +356,17 @@ void main() {
         emitsError(error),
       );
 
-      verify(mockClient.queryChannels(
+      verify(() => mockClient.queryChannels(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        paginationParams: paginationParams,
+            paginationParams: paginationParams,
-      )).called(1);
+          )).called(1);
     },
   );
 
   group('event controller test', () {
-    StreamController<Event> eventController;
+    late StreamController<Event> eventController;
     setUp(() {
       eventController = StreamController<Event>.broadcast();
     });
@@ -379,12 +381,12 @@ void main() {
           child: Offstage(),
         );
 
-        when(mockClient.on(any, any, any, any))
+        when(() => mockClient.on(any(), any(), any(), any()))
             .thenAnswer((_) => Stream.empty());
 
-        when(mockClient.on(
+        when(() => mockClient.on(
-          EventType.channelHidden,
+              EventType.channelHidden,
-        )).thenAnswer((_) => eventController.stream);
+            )).thenAnswer((_) => eventController.stream);
 
         await tester.pumpWidget(
           StreamChatCore(
@@ -399,23 +401,23 @@ void main() {
 
         final channels = _generateChannels(mockClient);
 
-        when(mockClient.queryChannels(
+        when(() => mockClient.queryChannels(
-          filter: anyNamed('filter'),
+              filter: any(named: 'filter'),
-          sort: anyNamed('sort'),
+              sort: any(named: 'sort'),
-          options: anyNamed('options'),
+              options: any(named: 'options'),
-          paginationParams: anyNamed('paginationParams'),
+              paginationParams: any(named: 'paginationParams'),
-        )).thenAnswer(
+            )).thenAnswer(
           (_) => Stream.value(channels),
         );
 
         await channelsBlocState.queryChannels();
 
-        verify(mockClient.queryChannels(
+        verify(() => mockClient.queryChannels(
-          filter: anyNamed('filter'),
+              filter: any(named: 'filter'),
-          sort: anyNamed('sort'),
+              sort: any(named: 'sort'),
-          options: anyNamed('options'),
+              options: any(named: 'options'),
-          paginationParams: anyNamed('paginationParams'),
+              paginationParams: any(named: 'paginationParams'),
-        )).called(1);
+            )).called(1);
 
         final channelHiddenEvent = Event(
           type: EventType.channelHidden,
@@ -435,7 +437,7 @@ void main() {
           ]),
         );
 
-        verify(mockClient.on(EventType.channelHidden)).called(1);
+        verify(() => mockClient.on(EventType.channelHidden)).called(1);
       },
     );
 
@@ -450,13 +452,13 @@ void main() {
           child: Offstage(),
         );
 
-        when(mockClient.on(any, any, any, any))
+        when(() => mockClient.on(any(), any(), any(), any()))
             .thenAnswer((_) => Stream.empty());
 
-        when(mockClient.on(
+        when(() => mockClient.on(
-          EventType.channelDeleted,
+              EventType.channelDeleted,
-          EventType.notificationRemovedFromChannel,
+              EventType.notificationRemovedFromChannel,
-        )).thenAnswer((_) => eventController.stream);
+            )).thenAnswer((_) => eventController.stream);
 
         await tester.pumpWidget(
           StreamChatCore(
@@ -471,31 +473,38 @@ void main() {
 
         final channels = _generateChannels(mockClient);
 
-        when(mockClient.queryChannels(
+        when(() => mockClient.queryChannels(
-          filter: anyNamed('filter'),
+              filter: any(named: 'filter'),
-          sort: anyNamed('sort'),
+              sort: any(named: 'sort'),
-          options: anyNamed('options'),
+              options: any(named: 'options'),
-          paginationParams: anyNamed('paginationParams'),
+              paginationParams: any(named: 'paginationParams'),
-        )).thenAnswer(
+            )).thenAnswer(
           (_) => Stream.value(channels),
         );
 
         await channelsBlocState.queryChannels();
 
-        verify(mockClient.queryChannels(
+        verify(() => mockClient.queryChannels(
-          filter: anyNamed('filter'),
+              filter: any(named: 'filter'),
-          sort: anyNamed('sort'),
+              sort: any(named: 'sort'),
-          options: anyNamed('options'),
+              options: any(named: 'options'),
-          paginationParams: anyNamed('paginationParams'),
+              paginationParams: any(named: 'paginationParams'),
-        )).called(1);
+            )).called(1);
 
         final channelDeletedOrNotificationRemovedEvent = Event(
-          channel: EventChannel(cid: channels.first.cid),
+          channel: EventChannel(
+            cid: channels.first.cid!,
+            updatedAt: DateTime.now(),
+            config: ChannelConfig(),
+            createdAt: DateTime.now(),
+            memberCount: 1,
+          ),
         );
 
         eventController.add(channelDeletedOrNotificationRemovedEvent);
 
-        final channelCid = channelDeletedOrNotificationRemovedEvent.channel.cid;
+        final channelCid =
+            channelDeletedOrNotificationRemovedEvent.channel?.cid;
         final newChannels = [...channels]
           ..removeWhere((it) => it.cid == channelCid);
 
@@ -507,10 +516,10 @@ void main() {
           ]),
         );
 
-        verify(mockClient.on(
+        verify(() => mockClient.on(
-          EventType.channelDeleted,
+              EventType.channelDeleted,
-          EventType.notificationRemovedFromChannel,
+              EventType.notificationRemovedFromChannel,
-        )).called(1);
+            )).called(1);
       },
     );
 
@@ -525,12 +534,12 @@ void main() {
           child: Offstage(),
         );
 
-        when(mockClient.on(any, any, any, any))
+        when(() => mockClient.on(any(), any(), any(), any()))
             .thenAnswer((_) => Stream.empty());
 
-        when(mockClient.on(
+        when(() => mockClient.on(
-          EventType.messageNew,
+              EventType.messageNew,
-        )).thenAnswer((_) => eventController.stream);
+            )).thenAnswer((_) => eventController.stream);
 
         await tester.pumpWidget(
           StreamChatCore(
@@ -545,23 +554,23 @@ void main() {
 
         final channels = _generateChannels(mockClient);
 
-        when(mockClient.queryChannels(
+        when(() => mockClient.queryChannels(
-          filter: anyNamed('filter'),
+              filter: any(named: 'filter'),
-          sort: anyNamed('sort'),
+              sort: any(named: 'sort'),
-          options: anyNamed('options'),
+              options: any(named: 'options'),
-          paginationParams: anyNamed('paginationParams'),
+              paginationParams: any(named: 'paginationParams'),
-        )).thenAnswer(
+            )).thenAnswer(
           (_) => Stream.value(channels),
         );
 
         await channelsBlocState.queryChannels();
 
-        verify(mockClient.queryChannels(
+        verify(() => mockClient.queryChannels(
-          filter: anyNamed('filter'),
+              filter: any(named: 'filter'),
-          sort: anyNamed('sort'),
+              sort: any(named: 'sort'),
-          options: anyNamed('options'),
+              options: any(named: 'options'),
-          paginationParams: anyNamed('paginationParams'),
+              paginationParams: any(named: 'paginationParams'),
-        )).called(1);
+            )).called(1);
 
         final messageNewEvent = Event(
           type: EventType.messageNew,
@@ -585,7 +594,7 @@ void main() {
           ]),
         );
 
-        verify(mockClient.on(EventType.messageNew)).called(1);
+        verify(() => mockClient.on(EventType.messageNew)).called(1);
       },
     );
 
@@ -609,16 +618,16 @@ void main() {
           shouldAddChannel: (e) => channels.map((it) => it.cid).contains(e.cid),
         );
 
-        when(mockClient.on(any, any, any, any))
+        when(() => mockClient.on(any(), any(), any(), any()))
             .thenAnswer((_) => Stream.empty());
 
-        when(mockClient.on(
+        when(() => mockClient.on(
-          EventType.channelHidden,
+              EventType.channelHidden,
-        )).thenAnswer((_) => hiddenChannelEventController.stream);
+            )).thenAnswer((_) => hiddenChannelEventController.stream);
 
-        when(mockClient.on(
+        when(() => mockClient.on(
-          EventType.messageNew,
+              EventType.messageNew,
-        )).thenAnswer((_) => eventController.stream);
+            )).thenAnswer((_) => eventController.stream);
 
         final messageNewEvent = Event(
           type: EventType.messageNew,
@@ -636,23 +645,23 @@ void main() {
           find.byKey(channelsBlocKey),
         );
 
-        when(mockClient.queryChannels(
+        when(() => mockClient.queryChannels(
-          filter: anyNamed('filter'),
+              filter: any(named: 'filter'),
-          sort: anyNamed('sort'),
+              sort: any(named: 'sort'),
-          options: anyNamed('options'),
+              options: any(named: 'options'),
-          paginationParams: anyNamed('paginationParams'),
+              paginationParams: any(named: 'paginationParams'),
-        )).thenAnswer(
+            )).thenAnswer(
           (_) => Stream.value(channels),
         );
 
         await channelsBlocState.queryChannels();
 
-        verify(mockClient.queryChannels(
+        verify(() => mockClient.queryChannels(
-          filter: anyNamed('filter'),
+              filter: any(named: 'filter'),
-          sort: anyNamed('sort'),
+              sort: any(named: 'sort'),
-          options: anyNamed('options'),
+              options: any(named: 'options'),
-          paginationParams: anyNamed('paginationParams'),
+              paginationParams: any(named: 'paginationParams'),
-        )).called(1);
+            )).called(1);
 
         final channelHiddenEvent = Event(
           type: EventType.channelHidden,
@@ -681,8 +690,8 @@ void main() {
           ]),
         );
 
-        verify(mockClient.on(EventType.channelHidden)).called(1);
+        verify(() => mockClient.on(EventType.channelHidden)).called(1);
-        verify(mockClient.on(EventType.messageNew)).called(1);
+        verify(() => mockClient.on(EventType.messageNew)).called(1);
       },
     );
 
@@ -703,14 +712,14 @@ void main() {
           shouldAddChannel: (_) => true,
         );
 
-        when(mockClient.state.channels).thenReturn(stateChannels);
+        when(() => mockClient.state.channels).thenReturn(stateChannels);
 
-        when(mockClient.on(any, any, any, any))
+        when(() => mockClient.on(any(), any(), any(), any()))
             .thenAnswer((_) => Stream.empty());
 
-        when(mockClient.on(
+        when(() => mockClient.on(
-          EventType.messageNew,
+              EventType.messageNew,
-        )).thenAnswer((_) => eventController.stream);
+            )).thenAnswer((_) => eventController.stream);
 
         await tester.pumpWidget(
           StreamChatCore(
@@ -723,23 +732,23 @@ void main() {
           find.byKey(channelsBlocKey),
         );
 
-        when(mockClient.queryChannels(
+        when(() => mockClient.queryChannels(
-          filter: anyNamed('filter'),
+              filter: any(named: 'filter'),
-          sort: anyNamed('sort'),
+              sort: any(named: 'sort'),
-          options: anyNamed('options'),
+              options: any(named: 'options'),
-          paginationParams: anyNamed('paginationParams'),
+              paginationParams: any(named: 'paginationParams'),
-        )).thenAnswer(
+            )).thenAnswer(
           (_) => Stream.value(channels),
         );
 
         await channelsBlocState.queryChannels();
 
-        verify(mockClient.queryChannels(
+        verify(() => mockClient.queryChannels(
-          filter: anyNamed('filter'),
+              filter: any(named: 'filter'),
-          sort: anyNamed('sort'),
+              sort: any(named: 'sort'),
-          options: anyNamed('options'),
+              options: any(named: 'options'),
-          paginationParams: anyNamed('paginationParams'),
+              paginationParams: any(named: 'paginationParams'),
-        )).called(1);
+            )).called(1);
 
         final messageNewEvent = Event(
           type: EventType.messageNew,
@@ -749,7 +758,7 @@ void main() {
         eventController.add(messageNewEvent);
 
         final newChannels = [...channels]
-          ..insert(0, stateChannels[stateChannels.keys.first]);
+          ..insert(0, stateChannels[stateChannels.keys.first]!);
 
         await expectLater(
           channelsBlocState.channelsStream,
@@ -759,7 +768,7 @@ void main() {
           ]),
         );
 
-        verify(mockClient.on(EventType.messageNew)).called(1);
+        verify(() => mockClient.on(EventType.messageNew)).called(1);
       },
     );
 
@@ -783,12 +792,12 @@ void main() {
           channelsComparator: channelComparator,
         );
 
-        when(mockClient.on(any, any, any, any))
+        when(() => mockClient.on(any(), any(), any(), any()))
             .thenAnswer((_) => Stream.empty());
 
-        when(mockClient.on(
+        when(() => mockClient.on(
-          EventType.messageNew,
+              EventType.messageNew,
-        )).thenAnswer((_) => eventController.stream);
+            )).thenAnswer((_) => eventController.stream);
 
         await tester.pumpWidget(
           StreamChatCore(
@@ -801,23 +810,23 @@ void main() {
           find.byKey(channelsBlocKey),
         );
 
-        when(mockClient.queryChannels(
+        when(() => mockClient.queryChannels(
-          filter: anyNamed('filter'),
+              filter: any(named: 'filter'),
-          sort: anyNamed('sort'),
+              sort: any(named: 'sort'),
-          options: anyNamed('options'),
+              options: any(named: 'options'),
-          paginationParams: anyNamed('paginationParams'),
+              paginationParams: any(named: 'paginationParams'),
-        )).thenAnswer(
+            )).thenAnswer(
           (_) => Stream.value(channels),
         );
 
         await channelsBlocState.queryChannels();
 
-        verify(mockClient.queryChannels(
+        verify(() => mockClient.queryChannels(
-          filter: anyNamed('filter'),
+              filter: any(named: 'filter'),
-          sort: anyNamed('sort'),
+              sort: any(named: 'sort'),
-          options: anyNamed('options'),
+              options: any(named: 'options'),
-          paginationParams: anyNamed('paginationParams'),
+              paginationParams: any(named: 'paginationParams'),
-        )).called(1);
+            )).called(1);
 
         final messageNewEvent = Event(
           type: EventType.messageNew,
@@ -836,7 +845,7 @@ void main() {
           ]),
         );
 
-        verify(mockClient.on(EventType.messageNew)).called(1);
+        verify(() => mockClient.on(EventType.messageNew)).called(1);
       },
     );
 

packages/stream_chat_flutter_core/test/lazy_load_scroll_view_test.dart

@@ -3,18 +3,6 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:stream_chat_flutter_core/src/lazy_load_scroll_view.dart';
 
 void main() {
-  test(
-    'should throw assertion error if child is null',
-    () async {
-      const lazyLoadScrollViewKey = Key('lazyLoadScrollView');
-      final lazyLoadScrollView = () => LazyLoadScrollView(
-            key: lazyLoadScrollViewKey,
-            child: null,
-          );
-      expect(lazyLoadScrollView, throwsA(isA<AssertionError>()));
-    },
-  );
-
   testWidgets(
     'should render LazyLoadScrollView if child is provided',
     (tester) async {

packages/stream_chat_flutter_core/test/matchers/channel_matcher.dart

@@ -7,7 +7,7 @@ Matcher isSameChannelAs(Channel targetChannel) =>
 
 class _IsSameChannelAs extends Matcher {
   const _IsSameChannelAs({
-    @required this.targetChannel,
+    required this.targetChannel,
   }) : assert(targetChannel != null, '');
 
   final Channel targetChannel;
@@ -26,7 +26,7 @@ Matcher isSameChannelListAs(List<Channel> targetChannelList) =>
 
 class _IsSameChannelListAs extends Matcher {
   const _IsSameChannelListAs({
-    @required this.targetChannelList,
+    required this.targetChannelList,
   }) : assert(targetChannelList != null, '');
 
   final List<Channel> targetChannelList;

packages/stream_chat_flutter_core/test/matchers/get_message_response_matcher.dart

@@ -1,4 +1,3 @@
-import 'package:meta/meta.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:stream_chat_flutter_core/stream_chat_flutter_core.dart';
 
@@ -7,15 +6,15 @@ Matcher isSameMessageResponseAs(GetMessageResponse targetResponse) =>
 
 class _IsSameMessageResponseAs extends Matcher {
   const _IsSameMessageResponseAs({
-    @required this.targetResponse,
+    required this.targetResponse,
-  }) : assert(targetResponse != null, '');
+  });
 
   final GetMessageResponse targetResponse;
 
   @override
   bool matches(covariant GetMessageResponse response, Map matchState) =>
       response.message.id == targetResponse.message.id &&
-      response.channel.cid == targetResponse.channel.cid;
+      response.channel?.cid == targetResponse.channel?.cid;
 
   @override
   Description describe(Description description) =>
@@ -28,15 +27,15 @@ Matcher isSameMessageResponseListAs(
 
 class _IsSameMessageResponseListAs extends Matcher {
   const _IsSameMessageResponseListAs({
-    @required this.targetResponseList,
+    required this.targetResponseList,
-  }) : assert(targetResponseList != null, '');
+  });
 
   final List<GetMessageResponse> targetResponseList;
 
   @override
   bool matches(
       covariant List<GetMessageResponse> responseList, Map matchState) {
-    bool matches = true;
+    var matches = true;
     for (var i = 0; i < responseList.length; i++) {
       final response = responseList[i];
       final targetResponse = targetResponseList[i];

packages/stream_chat_flutter_core/test/matchers/message_matcher.dart

@@ -7,7 +7,7 @@ Matcher isSameMessageAs(Message targetMessage) =>
 
 class _IsSameMessageAs extends Matcher {
   const _IsSameMessageAs({
-    @required this.targetMessage,
+    required this.targetMessage,
   }) : assert(targetMessage != null, '');
 
   final Message targetMessage;
@@ -26,7 +26,7 @@ Matcher isSameMessageListAs(List<Message> targetMessageList) =>
 
 class _IsSameMessageListAs extends Matcher {
   const _IsSameMessageListAs({
-    @required this.targetMessageList,
+    required this.targetMessageList,
   }) : assert(targetMessageList != null, '');
 
   final List<Message> targetMessageList;

packages/stream_chat_flutter_core/test/matchers/users_matcher.dart

@@ -6,7 +6,7 @@ Matcher isSameUserAs(User targetUser) => _IsSameUserAs(targetUser: targetUser);
 
 class _IsSameUserAs extends Matcher {
   const _IsSameUserAs({
-    @required this.targetUser,
+    required this.targetUser,
   }) : assert(targetUser != null, '');
 
   final User targetUser;
@@ -24,7 +24,7 @@ Matcher isSameUserListAs(List<User> targetUserList) =>
 
 class _IsSameUserListAs extends Matcher {
   const _IsSameUserListAs({
-    @required this.targetUserList,
+    required this.targetUserList,
   }) : assert(targetUserList != null, '');
 
   final List<User> targetUserList;

packages/stream_chat_flutter_core/test/message_list_core_test.dart

@@ -2,7 +2,7 @@ import 'dart:async';
 
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:mockito/mockito.dart';
+import 'package:mocktail/mocktail.dart';
 import 'package:stream_chat_flutter_core/src/message_list_core.dart';
 import 'package:stream_chat_flutter_core/stream_chat_flutter_core.dart';
 
@@ -62,61 +62,6 @@ void main() {
     return threads ? threadMessages : messages;
   }
 
-  test(
-    'should throw assertion error in case messageListBuilder is null',
-    () {
-      final messageListCore = () => MessageListCore(
-            messageListBuilder: null,
-            loadingBuilder: (BuildContext context) => Offstage(),
-            emptyBuilder: (BuildContext context) => Offstage(),
-            errorWidgetBuilder: (BuildContext context, Object error) =>
-                Offstage(),
-          );
-      expect(messageListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error in case loadingBuilder is null',
-    () {
-      final messageListCore = () => MessageListCore(
-            messageListBuilder: (_, __) => Offstage(),
-            loadingBuilder: null,
-            emptyBuilder: (BuildContext context) => Offstage(),
-            errorWidgetBuilder: (BuildContext context, Object error) =>
-                Offstage(),
-          );
-      expect(messageListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error in case emptyBuilder is null',
-    () {
-      final messageListCore = () => MessageListCore(
-            messageListBuilder: (_, __) => Offstage(),
-            loadingBuilder: (BuildContext context) => Offstage(),
-            emptyBuilder: null,
-            errorWidgetBuilder: (BuildContext context, Object error) =>
-                Offstage(),
-          );
-      expect(messageListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error in case errorWidgetBuilder is null',
-    () {
-      final messageListCore = () => MessageListCore(
-            messageListBuilder: (_, __) => Offstage(),
-            loadingBuilder: (BuildContext context) => Offstage(),
-            emptyBuilder: (BuildContext context) => Offstage(),
-            errorWidgetBuilder: null,
-          );
-      expect(messageListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
   testWidgets(
     'should throw if MessageListCore is used where StreamChannel is not present '
     'in the widget tree',
@@ -150,8 +95,11 @@ void main() {
       );
 
       final mockChannel = MockChannel();
+      when(() => mockChannel.initialized).thenAnswer((_) => Future.value(true));
 
-      when(mockChannel.state.isUpToDate).thenReturn(true);
+      when(() => mockChannel.state.isUpToDate).thenReturn(true);
+      when(() => mockChannel.state.messagesStream)
+          .thenAnswer((_) => Stream.value([]));
 
       await tester.pumpWidget(
         StreamChannel(
@@ -182,7 +130,10 @@ void main() {
 
       final mockChannel = MockChannel();
 
-      when(mockChannel.state.isUpToDate).thenReturn(true);
+      when(() => mockChannel.state.isUpToDate).thenReturn(true);
+      when(() => mockChannel.state.messagesStream)
+          .thenAnswer((_) => Stream.value([]));
+      when(() => mockChannel.initialized).thenAnswer((_) => Future.value(true));
 
       await tester.pumpWidget(
         StreamChannel(
@@ -213,11 +164,11 @@ void main() {
 
       final mockChannel = MockChannel();
 
-      when(mockChannel.state.isUpToDate).thenReturn(true);
+      when(() => mockChannel.state.isUpToDate).thenReturn(true);
-      when(mockChannel.initialized).thenAnswer((_) async => true);
+      when(() => mockChannel.initialized).thenAnswer((_) async => true);
 
       const error = 'Error! Error! Error!';
-      when(mockChannel.state.messagesStream)
+      when(() => mockChannel.state.messagesStream)
           .thenAnswer((_) => Stream.error(error));
 
       await tester.pumpWidget(
@@ -252,11 +203,11 @@ void main() {
 
       final mockChannel = MockChannel();
 
-      when(mockChannel.state.isUpToDate).thenReturn(true);
+      when(() => mockChannel.state.isUpToDate).thenReturn(true);
-      when(mockChannel.initialized).thenAnswer((_) async => true);
+      when(() => mockChannel.initialized).thenAnswer((_) async => true);
 
       const messages = <Message>[];
-      when(mockChannel.state.messagesStream)
+      when(() => mockChannel.state.messagesStream)
           .thenAnswer((_) => Stream.value(messages));
 
       await tester.pumpWidget(
@@ -291,11 +242,18 @@ void main() {
 
       final mockChannel = MockChannel();
 
-      when(mockChannel.state.isUpToDate).thenReturn(false);
+      when(() => mockChannel.state.isUpToDate).thenReturn(false);
-      when(mockChannel.initialized).thenAnswer((_) async => true);
+      when(() => mockChannel.initialized).thenAnswer((_) async => true);
+      when(() => mockChannel.query(
+            options: any(named: 'options'),
+            membersPagination: any(named: 'membersPagination'),
+            messagesPagination: any(named: 'messagesPagination'),
+            preferOffline: any(named: 'preferOffline'),
+            watchersPagination: any(named: 'watchersPagination'),
+          )).thenAnswer((_) async => ChannelState());
 
       const messages = <Message>[];
-      when(mockChannel.state.messagesStream)
+      when(() => mockChannel.state.messagesStream)
           .thenAnswer((_) => Stream.value(messages));
 
       await tester.pumpWidget(
@@ -335,11 +293,11 @@ void main() {
 
       final mockChannel = MockChannel();
 
-      when(mockChannel.state.isUpToDate).thenReturn(true);
+      when(() => mockChannel.state.isUpToDate).thenReturn(true);
-      when(mockChannel.initialized).thenAnswer((_) async => true);
+      when(() => mockChannel.initialized).thenAnswer((_) async => true);
 
       final messages = _generateMessages();
-      when(mockChannel.state.messagesStream)
+      when(() => mockChannel.state.messagesStream)
           .thenAnswer((_) => Stream.value(messages));
 
       await tester.pumpWidget(
@@ -382,13 +340,13 @@ void main() {
 
       final mockChannel = MockChannel();
 
-      when(mockChannel.state.isUpToDate).thenReturn(true);
+      when(() => mockChannel.state.isUpToDate).thenReturn(true);
-      when(mockChannel.initialized).thenAnswer((_) async => true);
+      when(() => mockChannel.initialized).thenAnswer((_) async => true);
 
       final threads = {parentMessage.id: messages};
 
-      when(mockChannel.state.threads).thenReturn(threads);
+      when(() => mockChannel.state.threads).thenReturn(threads);
-      when(mockChannel.state.threadsStream)
+      when(() => mockChannel.state.threadsStream)
           .thenAnswer((_) => Stream.value(threads));
 
       await tester.pumpWidget(

packages/stream_chat_flutter_core/test/message_search_bloc_test.dart

@@ -1,6 +1,6 @@
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:mockito/mockito.dart';
+import 'package:mocktail/mocktail.dart';
 import 'package:stream_chat/stream_chat.dart';
 import 'package:stream_chat_flutter_core/src/message_search_bloc.dart';
 import 'package:stream_chat_flutter_core/stream_chat_flutter_core.dart';
@@ -23,24 +23,12 @@ void main() {
             text: 'testTextData$index',
           )
           ..channel = ChannelModel(
-            cid: 'testCid',
+            cid: 'testCid:id',
           );
       },
     );
   }
 
-  test(
-    'should throw assertion error if child is null',
-    () async {
-      const messageSearchBlocKey = Key('messageSearchBloc');
-      final messageSearchBloc = () => MessageSearchBloc(
-            key: messageSearchBlocKey,
-            child: null,
-          );
-      expect(messageSearchBloc, throwsA(isA<AssertionError>()));
-    },
-  );
-
   testWidgets(
     'messageSearchBlocState.search() should throw if used where '
     'StreamChat is not present in the widget tree',
@@ -62,7 +50,7 @@ void main() {
       );
 
       try {
-        await usersBlocState.search();
+        await usersBlocState.search(filter: {});
       } catch (e) {
         expect(e, isInstanceOf<Exception>());
       }
@@ -93,30 +81,30 @@ void main() {
 
       final messageResponseList = _generateMessages();
 
-      when(mockClient.search(
+      when(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).thenAnswer(
+          )).thenAnswer(
         (_) async => SearchMessagesResponse()..results = messageResponseList,
       );
 
-      messageSearchBlocState.search();
+      messageSearchBlocState.search(filter: {});
 
       await expectLater(
         messageSearchBlocState.messagesStream,
         emits(isSameMessageResponseListAs(messageResponseList)),
       );
 
-      verify(mockClient.search(
+      verify(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -144,28 +132,28 @@ void main() {
       );
 
       const error = 'Error! Error! Error!';
-      when(mockClient.search(
+      when(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).thenThrow(error);
+          )).thenThrow(error);
 
-      messageSearchBlocState.search();
+      messageSearchBlocState.search(filter: {});
 
       await expectLater(
         messageSearchBlocState.messagesStream,
         emitsError(error),
       );
 
-      verify(mockClient.search(
+      verify(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -196,47 +184,47 @@ void main() {
 
       final messageResponseList = _generateMessages();
 
-      when(mockClient.search(
+      when(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).thenAnswer(
+          )).thenAnswer(
         (_) async => SearchMessagesResponse()..results = messageResponseList,
       );
 
-      messageSearchBlocState.search();
+      messageSearchBlocState.search(filter: {});
 
       await expectLater(
         messageSearchBlocState.messagesStream,
         emits(isSameMessageResponseListAs(messageResponseList)),
       );
 
-      verify(mockClient.search(
+      verify(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).called(1);
+          )).called(1);
 
       final offset = messageResponseList.length;
       final paginatedMessageResponseList = _generateMessages(offset: offset);
       final pagination = PaginationParams(offset: offset);
 
-      when(mockClient.search(
+      when(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).thenAnswer(
+          )).thenAnswer(
         (_) async =>
             SearchMessagesResponse()..results = paginatedMessageResponseList,
       );
 
-      messageSearchBlocState.search(pagination: pagination);
+      messageSearchBlocState.search(pagination: pagination, filter: {});
 
       await Future.wait([
         expectLater(
@@ -251,13 +239,13 @@ void main() {
         ),
       ]);
 
-      verify(mockClient.search(
+      verify(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -288,57 +276,57 @@ void main() {
 
       final messageResponseList = _generateMessages();
 
-      when(mockClient.search(
+      when(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).thenAnswer(
+          )).thenAnswer(
         (_) async => SearchMessagesResponse()..results = messageResponseList,
       );
 
-      messageSearchBlocState.search();
+      messageSearchBlocState.search(filter: {});
 
       await expectLater(
         messageSearchBlocState.messagesStream,
         emits(isSameMessageResponseListAs(messageResponseList)),
       );
 
-      verify(mockClient.search(
+      verify(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).called(1);
+          )).called(1);
 
       final offset = messageResponseList.length;
       final pagination = PaginationParams(offset: offset);
 
       const error = 'Error! Error! Error!';
-      when(mockClient.search(
+      when(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).thenThrow(error);
+          )).thenThrow(error);
 
-      messageSearchBlocState.search(pagination: pagination);
+      messageSearchBlocState.search(pagination: pagination, filter: {});
 
       await expectLater(
         messageSearchBlocState.queryMessagesLoading,
         emitsError(error),
       );
 
-      verify(mockClient.search(
+      verify(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).called(1);
+          )).called(1);
     },
   );
 }

packages/stream_chat_flutter_core/test/message_search_list_core_test.dart

@@ -1,8 +1,8 @@
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:mockito/mockito.dart';
+import 'package:mocktail/mocktail.dart';
-import 'package:stream_chat_flutter_core/stream_chat_flutter_core.dart';
 import 'package:stream_chat_flutter_core/src/message_search_list_core.dart';
+import 'package:stream_chat_flutter_core/stream_chat_flutter_core.dart';
 
 import 'mocks.dart';
 
@@ -10,74 +10,21 @@ void main() {
   List<GetMessageResponse> _generateMessages({
     int count = 3,
     int offset = 0,
-  }) {
+  }) =>
-    return List.generate(
+      List.generate(
-      count,
+        count,
-      (index) {
+        (index) {
-        index = index + offset;
+          index = index + offset;
-        return GetMessageResponse()
+          return GetMessageResponse()
-          ..message = Message(
+            ..message = Message(
-            id: 'testId$index',
+              id: 'testId$index',
-            text: 'testTextData$index',
+              text: 'testTextData$index',
-          )
+            )
-          ..channel = ChannelModel(
+            ..channel = ChannelModel(
-            cid: 'testCid',
+              cid: 'test:Cid',
-          );
+            );
-      },
+        },
-    );
+      );
-  }
-
-  test(
-    'should throw assertion error in case childBuilder is null',
-    () {
-      final messageSearchListCore = () => MessageSearchListCore(
-            childBuilder: null,
-            loadingBuilder: (BuildContext context) => Offstage(),
-            emptyBuilder: (BuildContext context) => Offstage(),
-            errorBuilder: (BuildContext context, Object error) => Offstage(),
-          );
-      expect(messageSearchListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error in case loadingBuilder is null',
-    () {
-      final messageSearchListCore = () => MessageSearchListCore(
-            childBuilder: (List<GetMessageResponse> messages) => Offstage(),
-            loadingBuilder: null,
-            emptyBuilder: (BuildContext context) => Offstage(),
-            errorBuilder: (BuildContext context, Object error) => Offstage(),
-          );
-      expect(messageSearchListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error in case emptyBuilder is null',
-    () {
-      final messageSearchListCore = () => MessageSearchListCore(
-            childBuilder: (List<GetMessageResponse> messages) => Offstage(),
-            loadingBuilder: (BuildContext context) => Offstage(),
-            emptyBuilder: null,
-            errorBuilder: (BuildContext context, Object error) => Offstage(),
-          );
-      expect(messageSearchListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error in case errorBuilder is null',
-    () {
-      final messageSearchListCore = () => MessageSearchListCore(
-            childBuilder: (List<GetMessageResponse> messages) => Offstage(),
-            loadingBuilder: (BuildContext context) => Offstage(),
-            emptyBuilder: (BuildContext context) => Offstage(),
-            errorBuilder: null,
-          );
-      expect(messageSearchListCore, throwsA(isA<AssertionError>()));
-    },
-  );
 
   testWidgets(
     'should throw if MessageSearchListCore is used where MessageSearchBloc '
@@ -86,10 +33,11 @@ void main() {
       const messageSearchListCoreKey = Key('messageSearchListCore');
       final messageSearchListCore = MessageSearchListCore(
         key: messageSearchListCoreKey,
-        childBuilder: (List<GetMessageResponse> messages) => Offstage(),
+        childBuilder: (List<GetMessageResponse>? messages) => const Offstage(),
-        loadingBuilder: (BuildContext context) => Offstage(),
+        loadingBuilder: (BuildContext context) => const Offstage(),
-        emptyBuilder: (BuildContext context) => Offstage(),
+        emptyBuilder: (BuildContext context) => const Offstage(),
-        errorBuilder: (BuildContext context, Object error) => Offstage(),
+        errorBuilder: (BuildContext context, Object? error) => const Offstage(),
+        filters: const {},
       );
 
       await tester.pumpWidget(messageSearchListCore);
@@ -109,7 +57,8 @@ void main() {
         childBuilder: (List<GetMessageResponse> messages) => Offstage(),
         loadingBuilder: (BuildContext context) => Offstage(),
         emptyBuilder: (BuildContext context) => Offstage(),
-        errorBuilder: (BuildContext context, Object error) => Offstage(),
+        errorBuilder: (BuildContext context, Object? error) => Offstage(),
+        filters: {},
       );
 
       final mockClient = MockClient();
@@ -140,6 +89,7 @@ void main() {
         emptyBuilder: (BuildContext context) => Offstage(),
         errorBuilder: (BuildContext context, Object error) => Offstage(),
         messageSearchListController: controller,
+        filters: {},
       );
 
       expect(controller.loadData, isNull);
@@ -175,18 +125,19 @@ void main() {
         errorBuilder: (BuildContext context, Object error) => Offstage(
           key: errorWidgetKey,
         ),
+        filters: {},
       );
 
       final mockClient = MockClient();
 
       const error = 'Error! Error! Error!';
-      when(mockClient.search(
+      when(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).thenThrow(error);
+          )).thenThrow(error);
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -201,13 +152,13 @@ void main() {
 
       expect(find.byKey(errorWidgetKey), findsOneWidget);
 
-      verify(mockClient.search(
+      verify(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -223,18 +174,19 @@ void main() {
         loadingBuilder: (BuildContext context) => Offstage(),
         emptyBuilder: (BuildContext context) => Offstage(key: emptyWidgetKey),
         errorBuilder: (BuildContext context, Object error) => Offstage(),
+        filters: {},
       );
 
       final mockClient = MockClient();
 
       final messageResponseList = <GetMessageResponse>[];
-      when(mockClient.search(
+      when(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).thenAnswer(
+          )).thenAnswer(
         (_) async => SearchMessagesResponse()..results = messageResponseList,
       );
 
@@ -251,13 +203,13 @@ void main() {
 
       expect(find.byKey(emptyWidgetKey), findsOneWidget);
 
-      verify(mockClient.search(
+      verify(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -274,18 +226,19 @@ void main() {
         loadingBuilder: (BuildContext context) => Offstage(),
         emptyBuilder: (BuildContext context) => Offstage(),
         errorBuilder: (BuildContext context, Object error) => Offstage(),
+        filters: {},
       );
 
       final mockClient = MockClient();
 
       final messageResponseList = _generateMessages();
-      when(mockClient.search(
+      when(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).thenAnswer(
+          )).thenAnswer(
         (_) async => SearchMessagesResponse()..results = messageResponseList,
       );
 
@@ -302,13 +255,13 @@ void main() {
 
       expect(find.byKey(childWidgetKey), findsOneWidget);
 
-      verify(mockClient.search(
+      verify(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: anyNamed('paginationParams'),
+            paginationParams: any(named: 'paginationParams'),
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -324,25 +277,26 @@ void main() {
         childBuilder: (List<GetMessageResponse> messages) => Container(
           key: childWidgetKey,
           child: Text(
-            messages.map((e) => '${e.channel.cid}-${e.message.id}').join(','),
+            messages.map((e) => '${e.channel?.cid}-${e.message.id}').join(','),
           ),
         ),
         loadingBuilder: (BuildContext context) => Offstage(),
         emptyBuilder: (BuildContext context) => Offstage(),
         errorBuilder: (BuildContext context, Object error) => Offstage(),
         paginationParams: pagination,
+        filters: {},
       );
 
       final mockClient = MockClient();
 
       final messageResponseList = _generateMessages();
-      when(mockClient.search(
+      when(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).thenAnswer(
+          )).thenAnswer(
         (_) async => SearchMessagesResponse()..results = messageResponseList,
       );
 
@@ -364,19 +318,19 @@ void main() {
       expect(
         find.text(
           messageResponseList
-              .map((e) => '${e.channel.cid}-${e.message.id}')
+              .map((e) => '${e.channel?.cid}-${e.message.id}')
               .join(','),
         ),
         findsOneWidget,
       );
 
-      verify(mockClient.search(
+      verify(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).called(1);
+          )).called(1);
 
       final messageSearchListCoreState =
           tester.state<MessageSearchListCoreState>(
@@ -386,13 +340,13 @@ void main() {
       final offset = messageResponseList.length;
       final paginatedMessageResponseList = _generateMessages(offset: offset);
       final updatedPagination = pagination.copyWith(offset: offset);
-      when(mockClient.search(
+      when(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: updatedPagination,
+            paginationParams: updatedPagination,
-      )).thenAnswer(
+          )).thenAnswer(
         (_) async =>
             SearchMessagesResponse()..results = paginatedMessageResponseList,
       );
@@ -406,17 +360,17 @@ void main() {
         find.text([
           ...messageResponseList,
           ...paginatedMessageResponseList,
-        ].map((e) => '${e.channel.cid}-${e.message.id}').join(',')),
+        ].map((e) => '${e.channel?.cid}-${e.message.id}').join(',')),
         findsOneWidget,
       );
 
-      verify(mockClient.search(
+      verify(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: updatedPagination,
+            paginationParams: updatedPagination,
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -426,8 +380,8 @@ void main() {
     (tester) async {
       const pagination = PaginationParams();
 
-      StateSetter _stateSetter;
+      StateSetter? _stateSetter;
-      int limit = pagination.limit;
+      var limit = pagination.limit;
 
       const messageSearchListCoreKey = Key('messageSearchListCore');
       const childWidgetKey = Key('childWidget');
@@ -438,7 +392,7 @@ void main() {
               key: childWidgetKey,
               child: Text(
                 messages
-                    .map((e) => '${e.channel.cid}-${e.message.id}')
+                    .map((e) => '${e.channel?.cid}-${e.message.id}')
                     .join(','),
               ),
             ),
@@ -446,18 +400,19 @@ void main() {
             emptyBuilder: (BuildContext context) => Offstage(),
             errorBuilder: (BuildContext context, Object error) => Offstage(),
             paginationParams: pagination.copyWith(limit: limit),
+            filters: {},
           );
 
       final mockClient = MockClient();
 
       final messageResponseList = _generateMessages();
-      when(mockClient.search(
+      when(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).thenAnswer(
+          )).thenAnswer(
         (_) async => SearchMessagesResponse()..results = messageResponseList,
       );
 
@@ -483,32 +438,32 @@ void main() {
       expect(
         find.text(
           messageResponseList
-              .map((e) => '${e.channel.cid}-${e.message.id}')
+              .map((e) => '${e.channel?.cid}-${e.message.id}')
               .join(','),
         ),
         findsOneWidget,
       );
 
-      verify(mockClient.search(
+      verify(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: pagination,
+            paginationParams: pagination,
-      )).called(1);
+          )).called(1);
 
       // Rebuilding MessageSearchListCore with new pagination limit
-      _stateSetter(() => limit = 6);
+      _stateSetter?.call(() => limit = 6);
 
       final updatedMessageResponseList = _generateMessages(count: limit);
       final updatedPagination = pagination.copyWith(limit: limit);
-      when(mockClient.search(
+      when(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: updatedPagination,
+            paginationParams: updatedPagination,
-      )).thenAnswer(
+          )).thenAnswer(
         (_) async =>
             SearchMessagesResponse()..results = updatedMessageResponseList,
       );
@@ -518,18 +473,18 @@ void main() {
       expect(find.byKey(childWidgetKey), findsOneWidget);
       expect(
         find.text(updatedMessageResponseList
-            .map((e) => '${e.channel.cid}-${e.message.id}')
+            .map((e) => '${e.channel?.cid}-${e.message.id}')
             .join(',')),
         findsOneWidget,
       );
 
-      verify(mockClient.search(
+      verify(() => mockClient.search(
-        any,
+            any(),
-        query: anyNamed('query'),
+            query: any(named: 'query'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        messageFilters: anyNamed('messageFilters'),
+            messageFilters: any(named: 'messageFilters'),
-        paginationParams: updatedPagination,
+            paginationParams: updatedPagination,
-      )).called(1);
+          )).called(1);
     },
   );
 }

packages/stream_chat_flutter_core/test/mocks.dart

@@ -1,19 +1,20 @@
-import 'package:mockito/mockito.dart';
+import 'package:mocktail/mocktail.dart';
 import 'package:stream_chat/stream_chat.dart';
 
 class MockLogger extends Mock implements Logger {}
 
 class MockClient extends Mock implements StreamChatClient {
+  @override
   final Logger logger = MockLogger();
 
-  ClientState _state;
+  ClientState? _state;
 
   @override
   ClientState get state => _state ??= MockClientState();
 }
 
 class MockClientState extends Mock implements ClientState {
-  OwnUser _user;
+  OwnUser? _user;
 
   @override
   OwnUser get user => _user ??= OwnUser(
@@ -25,12 +26,12 @@ class MockClientState extends Mock implements ClientState {
 }
 
 class MockChannel extends Mock implements Channel {
-  ChannelClientState _state;
+  ChannelClientState? _state;
 
   @override
   ChannelClientState get state => _state ??= MockChannelState();
 
-  StreamChatClient _client;
+  StreamChatClient? _client;
 
   @override
   StreamChatClient get client => _client ??= MockClient();

packages/stream_chat_flutter_core/test/stream_channel_test.dart

@@ -3,7 +3,7 @@ import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:mockito/mockito.dart';
+import 'package:mocktail/mocktail.dart';
 import 'package:stream_chat_flutter_core/stream_chat_flutter_core.dart';
 
 import 'mocks.dart';
@@ -62,39 +62,13 @@ void main() {
     return threads ? threadMessages : messages;
   }
 
-  test(
-    'should throw assertion error if child is null',
-    () async {
-      final mockChannel = MockChannel();
-      const streamChannelKey = Key('streamChannel');
-      final streamChannel = () => StreamChannel(
-            key: streamChannelKey,
-            channel: mockChannel,
-            child: null,
-          );
-      expect(streamChannel, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error if channel is null',
-    () async {
-      const streamChannelKey = Key('streamChannel');
-      final streamChannel = () => StreamChannel(
-            key: streamChannelKey,
-            child: Offstage(),
-            channel: null,
-          );
-      expect(streamChannel, throwsA(isA<AssertionError>()));
-    },
-  );
-
   testWidgets(
     'should render StreamChannel if both channel and child is provided',
     (tester) async {
       final mockChannel = MockChannel();
       const streamChannelKey = Key('streamChannel');
       const childKey = Key('childKey');
+      when(() => mockChannel.initialized).thenAnswer((_) => Future.value(true));
       final streamChannel = StreamChannel(
         key: streamChannelKey,
         channel: mockChannel,
@@ -121,8 +95,13 @@ void main() {
       );
 
       final errorMessage = 'Error! Error! Error!';
-      final error = DioError(type: DioErrorType.response, error: errorMessage);
+      final error = DioError(
-      when(mockChannel.initialized).thenAnswer((_) => Future.error(error));
+        type: DioErrorType.response,
+        error: errorMessage,
+        requestOptions: RequestOptions(path: ''),
+      );
+      when(() => mockChannel.initialized)
+          .thenAnswer((_) => Future.error(error));
 
       await tester.pumpWidget(
         Directionality(
@@ -135,7 +114,7 @@ void main() {
 
       expect(find.text(errorMessage), findsOneWidget);
 
-      verify(mockChannel.initialized).called(1);
+      verify(() => mockChannel.initialized).called(1);
     },
   );
 
@@ -153,7 +132,7 @@ void main() {
         showLoading: true,
       );
 
-      when(mockChannel.initialized).thenAnswer((_) async => false);
+      when(() => mockChannel.initialized).thenAnswer((_) async => false);
 
       await tester.pumpWidget(
         Directionality(
@@ -166,7 +145,7 @@ void main() {
 
       expect(find.byType(CircularProgressIndicator), findsOneWidget);
 
-      verify(mockChannel.initialized).called(1);
+      verify(() => mockChannel.initialized).called(1);
     },
   );
 
@@ -183,15 +162,15 @@ void main() {
         initialMessageId: 'testInitialMessageId',
       );
 
-      when(mockChannel.initialized).thenAnswer((_) async => true);
+      when(() => mockChannel.initialized).thenAnswer((_) async => true);
       final messages = _generateMessages();
-      when(mockChannel.query(
+      when(() => mockChannel.query(
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        messagesPagination: anyNamed('messagesPagination'),
+            messagesPagination: any(named: 'messagesPagination'),
-        membersPagination: anyNamed('membersPagination'),
+            membersPagination: any(named: 'membersPagination'),
-        watchersPagination: anyNamed('watchersPagination'),
+            watchersPagination: any(named: 'watchersPagination'),
-        preferOffline: anyNamed('preferOffline'),
+            preferOffline: any(named: 'preferOffline'),
-      )).thenAnswer((_) async => ChannelState(messages: messages));
+          )).thenAnswer((_) async => ChannelState(messages: messages));
 
       await tester.pumpWidget(
         Directionality(
@@ -202,14 +181,14 @@ void main() {
 
       await tester.pumpAndSettle();
 
-      verify(mockChannel.initialized).called(1);
+      verify(() => mockChannel.initialized).called(1);
-      verify(mockChannel.query(
+      verify(() => mockChannel.query(
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        messagesPagination: anyNamed('messagesPagination'),
+            messagesPagination: any(named: 'messagesPagination'),
-        membersPagination: anyNamed('membersPagination'),
+            membersPagination: any(named: 'membersPagination'),
-        watchersPagination: anyNamed('watchersPagination'),
+            watchersPagination: any(named: 'watchersPagination'),
-        preferOffline: anyNamed('preferOffline'),
+            preferOffline: any(named: 'preferOffline'),
-      )).called(
+          )).called(
         2, // Fetching After messages + Fetching Before messages,
       );
     },
@@ -219,7 +198,7 @@ void main() {
     'should rebuild StreamChannel with updated widget data '
     'on calling setState()',
     (tester) async {
-      StateSetter _stateSetter;
+      StateSetter? _stateSetter;
 
       var initialMessageId = 'testInitialMessageId';
 
@@ -244,25 +223,25 @@ void main() {
         limit: 20,
       );
 
-      when(mockChannel.initialized).thenAnswer((_) async => true);
+      when(() => mockChannel.initialized).thenAnswer((_) async => true);
 
       final messages = _generateMessages();
 
-      when(mockChannel.query(
+      when(() => mockChannel.query(
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        messagesPagination: beforePagination,
+            messagesPagination: beforePagination,
-        membersPagination: anyNamed('membersPagination'),
+            membersPagination: any(named: 'membersPagination'),
-        watchersPagination: anyNamed('watchersPagination'),
+            watchersPagination: any(named: 'watchersPagination'),
-        preferOffline: anyNamed('preferOffline'),
+            preferOffline: any(named: 'preferOffline'),
-      )).thenAnswer((_) async => ChannelState(messages: messages));
+          )).thenAnswer((_) async => ChannelState(messages: messages));
 
-      when(mockChannel.query(
+      when(() => mockChannel.query(
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        messagesPagination: afterPagination,
+            messagesPagination: afterPagination,
-        membersPagination: anyNamed('membersPagination'),
+            membersPagination: any(named: 'membersPagination'),
-        watchersPagination: anyNamed('watchersPagination'),
+            watchersPagination: any(named: 'watchersPagination'),
-        preferOffline: anyNamed('preferOffline'),
+            preferOffline: any(named: 'preferOffline'),
-      )).thenAnswer((_) async => ChannelState(messages: messages));
+          )).thenAnswer((_) async => ChannelState(messages: messages));
 
       await tester.pumpWidget(
         Directionality(
@@ -279,23 +258,23 @@ void main() {
 
       await tester.pumpAndSettle();
 
-      verify(mockChannel.query(
+      verify(() => mockChannel.query(
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        messagesPagination: beforePagination,
+            messagesPagination: beforePagination,
-        membersPagination: anyNamed('membersPagination'),
+            membersPagination: any(named: 'membersPagination'),
-        watchersPagination: anyNamed('watchersPagination'),
+            watchersPagination: any(named: 'watchersPagination'),
-        preferOffline: anyNamed('preferOffline'),
+            preferOffline: any(named: 'preferOffline'),
-      )).called(1);
+          )).called(1);
 
-      verify(mockChannel.query(
+      verify(() => mockChannel.query(
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        messagesPagination: afterPagination,
+            messagesPagination: afterPagination,
-        membersPagination: anyNamed('membersPagination'),
+            membersPagination: any(named: 'membersPagination'),
-        watchersPagination: anyNamed('watchersPagination'),
+            watchersPagination: any(named: 'watchersPagination'),
-        preferOffline: anyNamed('preferOffline'),
+            preferOffline: any(named: 'preferOffline'),
-      )).called(1);
+          )).called(1);
 
-      _stateSetter(() => initialMessageId = 'testInitialMessageId2');
+      _stateSetter?.call(() => initialMessageId = 'testInitialMessageId2');
 
       final updatedBeforePagination = beforePagination.copyWith(
         lessThan: initialMessageId,
@@ -305,39 +284,39 @@ void main() {
         greaterThanOrEqual: initialMessageId,
       );
 
-      when(mockChannel.query(
+      when(() => mockChannel.query(
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        messagesPagination: updatedBeforePagination,
+            messagesPagination: updatedBeforePagination,
-        membersPagination: anyNamed('membersPagination'),
+            membersPagination: any(named: 'membersPagination'),
-        watchersPagination: anyNamed('watchersPagination'),
+            watchersPagination: any(named: 'watchersPagination'),
-        preferOffline: anyNamed('preferOffline'),
+            preferOffline: any(named: 'preferOffline'),
-      )).thenAnswer((_) async => ChannelState(messages: messages));
+          )).thenAnswer((_) async => ChannelState(messages: messages));
 
-      when(mockChannel.query(
+      when(() => mockChannel.query(
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        messagesPagination: updatedAfterPagination,
+            messagesPagination: updatedAfterPagination,
-        membersPagination: anyNamed('membersPagination'),
+            membersPagination: any(named: 'membersPagination'),
-        watchersPagination: anyNamed('watchersPagination'),
+            watchersPagination: any(named: 'watchersPagination'),
-        preferOffline: anyNamed('preferOffline'),
+            preferOffline: any(named: 'preferOffline'),
-      )).thenAnswer((_) async => ChannelState(messages: messages));
+          )).thenAnswer((_) async => ChannelState(messages: messages));
 
       await tester.pumpAndSettle();
 
-      verify(mockChannel.query(
+      verify(() => mockChannel.query(
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        messagesPagination: updatedBeforePagination,
+            messagesPagination: updatedBeforePagination,
-        membersPagination: anyNamed('membersPagination'),
+            membersPagination: any(named: 'membersPagination'),
-        watchersPagination: anyNamed('watchersPagination'),
+            watchersPagination: any(named: 'watchersPagination'),
-        preferOffline: anyNamed('preferOffline'),
+            preferOffline: any(named: 'preferOffline'),
-      )).called(1);
+          )).called(1);
 
-      verify(mockChannel.query(
+      verify(() => mockChannel.query(
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        messagesPagination: updatedAfterPagination,
+            messagesPagination: updatedAfterPagination,
-        membersPagination: anyNamed('membersPagination'),
+            membersPagination: any(named: 'membersPagination'),
-        watchersPagination: anyNamed('watchersPagination'),
+            watchersPagination: any(named: 'watchersPagination'),
-        preferOffline: anyNamed('preferOffline'),
+            preferOffline: any(named: 'preferOffline'),
-      )).called(1);
+          )).called(1);
     },
   );
 }

packages/stream_chat_flutter_core/test/stream_chat_core_test.dart

@@ -2,7 +2,7 @@ import 'dart:async';
 
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:mockito/mockito.dart';
+import 'package:mocktail/mocktail.dart';
 import 'package:stream_chat_flutter_core/stream_chat_flutter_core.dart';
 
 import 'mocks.dart';
@@ -12,29 +12,6 @@ class MockOnBackgroundEventReceived extends Mock {
 }
 
 void main() {
-  test(
-    'should throw assertion error in case client is null',
-    () {
-      final streamChatCore = () => StreamChatCore(
-            client: null,
-            child: Offstage(),
-          );
-      expect(streamChatCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error in case child is null',
-    () {
-      final mockClient = MockClient();
-      final streamChatCore = () => StreamChatCore(
-            client: mockClient,
-            child: null,
-          );
-      expect(streamChatCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
   testWidgets(
     'should render StreamChatCore if both client and child is provided',
     (tester) async {
@@ -92,7 +69,7 @@ void main() {
       expect(find.byKey(streamChatCoreKey), findsOneWidget);
       expect(find.byKey(childKey), findsOneWidget);
 
-      when(mockClient.disconnect()).thenAnswer((_) async {
+      when(() => mockClient.disconnect()).thenAnswer((_) async {
         return;
       });
 
@@ -102,7 +79,7 @@ void main() {
 
       streamChatCoreState.didChangeAppLifecycleState(AppLifecycleState.paused);
 
-      verify(mockClient.disconnect()).called(1);
+      verify(() => mockClient.disconnect()).called(1);
     },
   );
 
@@ -131,8 +108,8 @@ void main() {
         expect(find.byKey(childKey), findsOneWidget);
 
         final event = Event();
-        when(mockClient.on()).thenAnswer((_) => Stream.value(event));
+        when(() => mockClient.on()).thenAnswer((_) => Stream.value(event));
-        when(mockClient.disconnect()).thenAnswer((_) async {
+        when(() => mockClient.disconnect()).thenAnswer((_) async {
           return;
         });
 
@@ -143,14 +120,14 @@ void main() {
         streamChatCoreState
             .didChangeAppLifecycleState(AppLifecycleState.paused);
 
-        await untilCalled(mockOnBackgroundEventReceived.call(event));
+        await untilCalled(() => mockOnBackgroundEventReceived.call(event));
 
-        verify(mockOnBackgroundEventReceived.call(event)).called(1);
+        verify(() => mockOnBackgroundEventReceived.call(event)).called(1);
 
         await Future.delayed(backgroundKeepAlive);
 
-        verify(mockClient.disconnect()).called(1);
+        verify(() => mockClient.disconnect()).called(1);
-        verifyNever(mockOnBackgroundEventReceived.call(event));
+        verifyNever(() => mockOnBackgroundEventReceived.call(event));
       });
     },
   );
@@ -180,7 +157,7 @@ void main() {
         expect(find.byKey(childKey), findsOneWidget);
 
         final event = Event();
-        when(mockClient.on()).thenAnswer((_) => Stream.value(event));
+        when(() => mockClient.on()).thenAnswer((_) => Stream.value(event));
 
         final streamChatCoreState = tester.state<StreamChatCoreState>(
           find.byKey(streamChatCoreKey),
@@ -189,14 +166,14 @@ void main() {
         streamChatCoreState
             .didChangeAppLifecycleState(AppLifecycleState.paused);
 
-        await untilCalled(mockOnBackgroundEventReceived.call(event));
+        await untilCalled(() => mockOnBackgroundEventReceived.call(event));
 
-        verify(mockOnBackgroundEventReceived.call(event)).called(1);
+        verify(() => mockOnBackgroundEventReceived.call(event)).called(1);
 
         streamChatCoreState
             .didChangeAppLifecycleState(AppLifecycleState.resumed);
 
-        verifyNever(mockOnBackgroundEventReceived.call(event));
+        verifyNever(() => mockOnBackgroundEventReceived.call(event));
       });
     },
   );
@@ -222,9 +199,10 @@ void main() {
         expect(find.byKey(childKey), findsOneWidget);
 
         final event = Event();
-        when(mockClient.on()).thenAnswer((_) => Stream.value(event));
+        when(() => mockClient.on()).thenAnswer((_) => Stream.value(event));
-        when(mockClient.connect()).thenAnswer((_) async => event);
+        when(() => mockClient.connect()).thenAnswer((_) async => event);
-        when(mockClient.wsConnectionStatus)
+        when(mockClient.disconnect).thenAnswer((_) async => null);
+        when(() => mockClient.wsConnectionStatus)
             .thenReturn(ConnectionStatus.disconnected);
 
         final streamChatCoreState = tester.state<StreamChatCoreState>(
@@ -239,7 +217,7 @@ void main() {
         streamChatCoreState
             .didChangeAppLifecycleState(AppLifecycleState.resumed);
 
-        verify(mockClient.connect()).called(1);
+        verify(() => mockClient.connect()).called(1);
       });
     },
   );
@@ -265,7 +243,7 @@ void main() {
         expect(find.byKey(streamChatCoreKey), findsOneWidget);
         expect(find.byKey(childKey), findsOneWidget);
 
-        when(mockClient.state.userStream)
+        when(() => mockClient.state.userStream)
             .thenAnswer((_) => userController.stream);
 
         final streamChatCoreState = tester.state<StreamChatCoreState>(

packages/stream_chat_flutter_core/test/user_list_core_test.dart

@@ -1,6 +1,6 @@
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:mockito/mockito.dart';
+import 'package:mocktail/mocktail.dart';
 import 'package:stream_chat_flutter_core/src/user_list_core.dart';
 import 'package:stream_chat_flutter_core/stream_chat_flutter_core.dart';
 
@@ -33,58 +33,6 @@ void main() {
     );
   }
 
-  test(
-    'should throw assertion error in case listBuilder is null',
-    () {
-      final userListCore = () => UserListCore(
-            listBuilder: null,
-            loadingBuilder: (BuildContext context) => Offstage(),
-            emptyBuilder: (BuildContext context) => Offstage(),
-            errorBuilder: (Object error) => Offstage(),
-          );
-      expect(userListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error in case loadingBuilder is null',
-    () {
-      final userListCore = () => UserListCore(
-            listBuilder: (_, __) => Offstage(),
-            loadingBuilder: null,
-            emptyBuilder: (BuildContext context) => Offstage(),
-            errorBuilder: (Object error) => Offstage(),
-          );
-      expect(userListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error in case emptyBuilder is null',
-    () {
-      final userListCore = () => UserListCore(
-            listBuilder: (_, __) => Offstage(),
-            loadingBuilder: (BuildContext context) => Offstage(),
-            emptyBuilder: null,
-            errorBuilder: (Object error) => Offstage(),
-          );
-      expect(userListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
-  test(
-    'should throw assertion error in case errorBuilder is null',
-    () {
-      final userListCore = () => UserListCore(
-            listBuilder: (_, __) => Offstage(),
-            loadingBuilder: (BuildContext context) => Offstage(),
-            emptyBuilder: (BuildContext context) => Offstage(),
-            errorBuilder: null,
-          );
-      expect(userListCore, throwsA(isA<AssertionError>()));
-    },
-  );
-
   testWidgets(
     'should throw if UserListCore is used where UsersBloc is not present '
     'in the widget tree',
@@ -183,12 +131,12 @@ void main() {
       final mockClient = MockClient();
 
       const error = 'Error! Error! Error!';
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).thenThrow(error);
+          )).thenThrow(error);
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -203,12 +151,12 @@ void main() {
 
       expect(find.byKey(errorWidgetKey), findsOneWidget);
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -228,12 +176,12 @@ void main() {
       final mockClient = MockClient();
 
       const users = <User>[];
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).thenAnswer((_) async => QueryUsersResponse()..users = users);
+          )).thenAnswer((_) async => QueryUsersResponse()..users = users);
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -248,12 +196,12 @@ void main() {
 
       expect(find.byKey(emptyWidgetKey), findsOneWidget);
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -273,12 +221,12 @@ void main() {
       final mockClient = MockClient();
 
       final users = _generateUsers();
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).thenAnswer((_) async => QueryUsersResponse()..users = users);
+          )).thenAnswer((_) async => QueryUsersResponse()..users = users);
 
       await tester.pumpWidget(
         StreamChatCore(
@@ -293,12 +241,12 @@ void main() {
 
       expect(find.byKey(listWidgetKey), findsOneWidget);
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -314,7 +262,7 @@ void main() {
           child: ListView(
             children: items.map((e) {
               return Container(
-                key: Key(e.key),
+                key: Key(e.key ?? ''),
                 child: e.when(
                   headerItem: (heading) => Text(heading),
                   userItem: (user) => Text(user.id),
@@ -332,12 +280,12 @@ void main() {
       final mockClient = MockClient();
 
       final users = _generateUsers();
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).thenAnswer((_) async => QueryUsersResponse()..users = users);
+          )).thenAnswer((_) async => QueryUsersResponse()..users = users);
 
       await tester.pumpWidget(
         Directionality(
@@ -359,12 +307,12 @@ void main() {
         expect(find.byKey(Key('USER-${user.id}')), findsOneWidget);
       }
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -382,7 +330,7 @@ void main() {
           child: ListView(
             children: items.map((e) {
               return Container(
-                key: Key(e.key),
+                key: Key(e.key ?? ''),
                 child: e.when(
                   headerItem: (heading) => Text(heading),
                   userItem: (user) => Text(user.id),
@@ -401,12 +349,12 @@ void main() {
       final mockClient = MockClient();
 
       final users = _generateUsers();
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).thenAnswer((_) async => QueryUsersResponse()..users = users);
+          )).thenAnswer((_) async => QueryUsersResponse()..users = users);
 
       await tester.pumpWidget(
         Directionality(
@@ -428,12 +376,12 @@ void main() {
         expect(find.byKey(Key('USER-${user.id}')), findsOneWidget);
       }
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).called(1);
+          )).called(1);
 
       final userListCoreState = tester.state<UserListCoreState>(
         find.byKey(userListCoreKey),
@@ -442,12 +390,14 @@ void main() {
       final offset = users.length;
       final paginatedUsers = _generateUsers(offset: offset);
       final updatedPagination = pagination.copyWith(offset: offset);
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+                filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+                sort: any(named: 'sort'),
-        options: anyNamed('options'),
+                options: any(named: 'options'),
-        pagination: updatedPagination,
+                pagination: updatedPagination,
-      )).thenAnswer((_) async => QueryUsersResponse()..users = paginatedUsers);
+              ))
+          .thenAnswer(
+              (_) async => QueryUsersResponse()..users = paginatedUsers);
 
       await userListCoreState.paginateData();
 
@@ -458,12 +408,12 @@ void main() {
         expect(find.byKey(Key('USER-${user.id}')), findsOneWidget);
       }
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: updatedPagination,
+            pagination: updatedPagination,
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -473,7 +423,7 @@ void main() {
     (tester) async {
       const pagination = PaginationParams();
 
-      StateSetter _stateSetter;
+      StateSetter? _stateSetter;
       int limit = pagination.limit;
 
       const userListCoreKey = Key('userListCore');
@@ -485,7 +435,7 @@ void main() {
               child: ListView(
                 children: items.map((e) {
                   return Container(
-                    key: Key(e.key),
+                    key: Key(e.key ?? ''),
                     child: e.when(
                       headerItem: (heading) => Text(heading),
                       userItem: (user) => Text(user.id),
@@ -504,12 +454,12 @@ void main() {
       final mockClient = MockClient();
 
       final users = _generateUsers();
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).thenAnswer((_) async => QueryUsersResponse()..users = users);
+          )).thenAnswer((_) async => QueryUsersResponse()..users = users);
 
       await tester.pumpWidget(
         Directionality(
@@ -535,24 +485,25 @@ void main() {
         expect(find.byKey(Key('USER-${user.id}')), findsOneWidget);
       }
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).called(1);
+          )).called(1);
 
       // Rebuilding UserListCore with new pagination limit
-      _stateSetter(() => limit = 6);
+      _stateSetter?.call(() => limit = 6);
 
       final updatedUsers = _generateUsers(count: limit);
       final updatedPagination = pagination.copyWith(limit: limit);
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+                filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+                sort: any(named: 'sort'),
-        options: anyNamed('options'),
+                options: any(named: 'options'),
-        pagination: updatedPagination,
+                pagination: updatedPagination,
-      )).thenAnswer((_) async => QueryUsersResponse()..users = updatedUsers);
+              ))
+          .thenAnswer((_) async => QueryUsersResponse()..users = updatedUsers);
 
       await tester.pumpAndSettle();
 
@@ -561,12 +512,12 @@ void main() {
         expect(find.byKey(Key('USER-${user.id}')), findsOneWidget);
       }
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: updatedPagination,
+            pagination: updatedPagination,
-      )).called(1);
+          )).called(1);
     },
   );
 }

packages/stream_chat_flutter_core/test/users_bloc_test.dart

@@ -1,9 +1,9 @@
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:mocktail/mocktail.dart';
 import 'package:stream_chat/stream_chat.dart';
 import 'package:stream_chat_flutter_core/src/stream_chat_core.dart';
 import 'package:stream_chat_flutter_core/src/users_bloc.dart';
-import 'package:mockito/mockito.dart';
 
 import 'matchers/users_matcher.dart';
 import 'mocks.dart';
@@ -31,18 +31,6 @@ void main() {
     );
   }
 
-  test(
-    'should throw assertion error if child is null',
-    () async {
-      const usersBlocKey = Key('usersBloc');
-      final usersBloc = () => UsersBloc(
-            key: usersBlocKey,
-            child: null,
-          );
-      expect(usersBloc, throwsA(isA<AssertionError>()));
-    },
-  );
-
   testWidgets(
     'usersBlocState.queryUsers() should throw if used where '
     'StreamChat is not present in the widget tree',
@@ -96,12 +84,12 @@ void main() {
 
       final users = _generateUsers();
 
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).thenAnswer((_) async => QueryUsersResponse()..users = users);
+          )).thenAnswer((_) async => QueryUsersResponse()..users = users);
 
       usersBlocState.queryUsers();
 
@@ -110,12 +98,12 @@ void main() {
         emits(isSameUserListAs(users)),
       );
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -145,12 +133,12 @@ void main() {
 
       final error = 'Error! Error! Error!';
 
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).thenThrow(error);
+          )).thenThrow(error);
 
       usersBlocState.queryUsers();
 
@@ -159,12 +147,12 @@ void main() {
         emitsError(error),
       );
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -195,12 +183,12 @@ void main() {
 
       final users = _generateUsers();
 
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).thenAnswer((_) async => QueryUsersResponse()..users = users);
+          )).thenAnswer((_) async => QueryUsersResponse()..users = users);
 
       usersBlocState.queryUsers();
 
@@ -209,23 +197,25 @@ void main() {
         emits(isSameUserListAs(users)),
       );
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).called(1);
+          )).called(1);
 
       final offset = users.length;
       final paginatedUsers = _generateUsers(offset: offset);
       final pagination = PaginationParams(offset: offset);
 
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+                filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+                sort: any(named: 'sort'),
-        options: anyNamed('options'),
+                options: any(named: 'options'),
-        pagination: pagination,
+                pagination: pagination,
-      )).thenAnswer((_) async => QueryUsersResponse()..users = paginatedUsers);
+              ))
+          .thenAnswer(
+              (_) async => QueryUsersResponse()..users = paginatedUsers);
 
       usersBlocState.queryUsers(pagination: pagination);
 
@@ -240,12 +230,12 @@ void main() {
         ),
       ]);
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: pagination,
+            pagination: pagination,
-      )).called(1);
+          )).called(1);
     },
   );
 
@@ -276,12 +266,12 @@ void main() {
 
       final users = _generateUsers();
 
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).thenAnswer((_) async => QueryUsersResponse()..users = users);
+          )).thenAnswer((_) async => QueryUsersResponse()..users = users);
 
       usersBlocState.queryUsers();
 
@@ -290,24 +280,24 @@ void main() {
         emits(isSameUserListAs(users)),
       );
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: anyNamed('pagination'),
+            pagination: any(named: 'pagination'),
-      )).called(1);
+          )).called(1);
 
       final offset = users.length;
       final pagination = PaginationParams(offset: offset);
 
       final error = 'Error! Error! Error!';
 
-      when(mockClient.queryUsers(
+      when(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: pagination,
+            pagination: pagination,
-      )).thenThrow(error);
+          )).thenThrow(error);
 
       usersBlocState.queryUsers(pagination: pagination);
 
@@ -316,12 +306,12 @@ void main() {
         emitsError(error),
       );
 
-      verify(mockClient.queryUsers(
+      verify(() => mockClient.queryUsers(
-        filter: anyNamed('filter'),
+            filter: any(named: 'filter'),
-        sort: anyNamed('sort'),
+            sort: any(named: 'sort'),
-        options: anyNamed('options'),
+            options: any(named: 'options'),
-        pagination: pagination,
+            pagination: pagination,
-      )).called(1);
+          )).called(1);
     },
   );
 }