add reaction test

packages/stream_chat/test/src/core/models/reaction_test.dart

@@ -47,5 +47,108 @@ void main() {
         },
       );
     });
+
+    test('copyWith', () {
+      final reaction = Reaction.fromJson(jsonFixture('reaction.json'));
+      var newReaction = reaction.copyWith();
+      expect(newReaction.messageId, '76cd8c82-b557-4e48-9d12-87995d3a0e04');
+      expect(
+          newReaction.createdAt, DateTime.parse('2020-01-28T22:17:31.108742Z'));
+      expect(newReaction.type, 'wow');
+      expect(
+        newReaction.user?.toJson(),
+        User(id: '2de0297c-f3f2-489d-b930-ef77342edccf', extraData: const {
+          'image': 'https://randomuser.me/api/portraits/women/45.jpg',
+          'name': 'Daisy Morgan',
+        }).toJson(),
+      );
+      expect(newReaction.score, 1);
+      expect(newReaction.userId, '2de0297c-f3f2-489d-b930-ef77342edccf');
+      expect(
+          newReaction.extraData, {'updated_at': '2020-01-28T22:17:31.108742Z'});
+
+      newReaction = reaction.copyWith(
+        type: 'lol',
+        createdAt: DateTime.parse('2021-01-28T22:17:31.108742Z'),
+        extraData: {},
+        messageId: 'test',
+        score: 2,
+        user: User(id: 'test'),
+        userId: 'test',
+      );
+
+      expect(
+        newReaction.type,
+        'lol',
+      );
+      expect(
+        newReaction.createdAt,
+        DateTime.parse('2021-01-28T22:17:31.108742Z'),
+      );
+      expect(
+        newReaction.extraData,
+        {},
+      );
+      expect(
+        newReaction.messageId,
+        'test',
+      );
+      expect(
+        newReaction.score,
+        2,
+      );
+      expect(
+        newReaction.user,
+        User(id: 'test'),
+      );
+      expect(
+        newReaction.userId,
+        'test',
+      );
+    });
+
+    test('merge', () {
+      final reaction = Reaction.fromJson(jsonFixture('reaction.json'));
+      final newReaction = reaction.merge(
+        Reaction(
+          type: 'lol',
+          createdAt: DateTime.parse('2021-01-28T22:17:31.108742Z'),
+          extraData: {},
+          messageId: 'test',
+          score: 2,
+          user: User(id: 'test'),
+          userId: 'test',
+        ),
+      );
+
+      expect(
+        newReaction.type,
+        'lol',
+      );
+      expect(
+        newReaction.createdAt,
+        DateTime.parse('2021-01-28T22:17:31.108742Z'),
+      );
+      expect(
+        newReaction.extraData,
+        {},
+      );
+      expect(
+        newReaction.messageId,
+        'test',
+      );
+      expect(
+        newReaction.score,
+        2,
+      );
+      expect(
+        newReaction.user,
+        User(id: 'test'),
+      );
+      expect(
+        newReaction.userId,
+        'test',
+      );
+    });
   });
 }