chore: use isConnected flag instead of checking db value.

Signed-off-by: xsahil03x <[email protected]>

packages/stream_chat/test/src/db/chat_persistence_client_test.dart

@@ -12,6 +12,9 @@ import 'package:stream_chat/src/db/chat_persistence_client.dart';
 import 'package:test/test.dart';
 
 class TestPersistenceClient extends ChatPersistenceClient {
+  @override
+  bool get isConnected => throw UnimplementedError();
+
   @override
   Future<void> connect(String userId) => throw UnimplementedError();
 

packages/stream_chat_persistence/lib/src/stream_chat_persistence_client.dart

@@ -58,7 +58,7 @@ class StreamChatPersistenceClient extends ChatPersistenceClient {
 
   bool get _debugIsConnected {
     assert(() {
-      if (db == null) {
+      if (!isConnected) {
         throw StateError('''
         $runtimeType hasn't been connected yet or used after `disconnect` 
         was called. Consider calling `connect` to create a connection. 
@@ -408,7 +408,7 @@ class StreamChatPersistenceClient extends ChatPersistenceClient {
   @override
   Future<void> disconnect({bool flush = false}) async {
     _logger.info('disconnect');
-    if (db != null) {
+    if (isConnected) {
       _logger.info('Disconnecting');
       if (flush) {
         _logger.info('Flushing');

packages/stream_chat_persistence/test/stream_chat_persistence_client_test.dart

@@ -16,9 +16,9 @@ void main() {
     const userId = 'testUserId';
     test('successfully connects with the Database', () async {
       final client = StreamChatPersistenceClient(logLevel: Level.ALL);
-      expect(client.db, isNull);
+      expect(client.isConnected, false);
       await client.connect(userId, databaseProvider: testDatabaseProvider);
-      expect(client.db, isNotNull);
+      expect(client.isConnected, true);
       expect(client.db, isA<DriftChatDatabase>());
       expect(client.db!.userId, userId);
 
@@ -29,10 +29,9 @@ void main() {
 
     test('throws if already connected', () async {
       final client = StreamChatPersistenceClient(logLevel: Level.ALL);
-      expect(client.db, isNull);
+      expect(client.isConnected, false);
       await client.connect(userId, databaseProvider: testDatabaseProvider);
-      expect(client.db, isNotNull);
-      expect(client.db, isNotNull);
+      expect(client.isConnected, true);
       expect(client.db, isA<DriftChatDatabase>());
       expect(client.db!.userId, userId);
       expect(
@@ -50,9 +49,9 @@ void main() {
     const userId = 'testUserId';
     final client = StreamChatPersistenceClient(logLevel: Level.ALL);
     await client.connect(userId, databaseProvider: testDatabaseProvider);
-    expect(client.db, isNotNull);
+    expect(client.isConnected, true);
     await client.disconnect(flush: true);
-    expect(client.db, isNull);
+    expect(client.isConnected, false);
   });
 
   test('client function throws stateError if db is not yet connected', () {