started unit test for MusicDataStore

lib/core/error/failures.dart

@@ -5,7 +5,6 @@ abstract class Failure extends Equatable {
   List<Object> get props => [];
 }
 
-class IndexFailure extends Failure {
-  @override
-  List<Object> get props => [];
-}
+class IndexFailure extends Failure {}
+
+class GenericFailure extends Failure { }

test/presentation/state/music_data_store_test.dart

@@ -0,0 +1,132 @@
+import 'package:dartz/dartz.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:meta/meta.dart';
+import 'package:mockito/mockito.dart';
+import 'package:mucke/core/error/failures.dart';
+import 'package:mucke/domain/entities/artist.dart';
+import 'package:mucke/domain/repositories/music_data_repository.dart';
+import 'package:mucke/presentation/state/music_data_store.dart';
+
+class MockMusicDataRepository extends Mock implements MusicDataRepository {}
+
+class MockInitMusicDataStore extends MusicDataStore {
+  MockInitMusicDataStore({@required MusicDataRepository musicDataRepository})
+      : super(musicDataRepository: musicDataRepository);
+
+  int fetchArtistsCalled = 0;
+  int fetchAlbumsCalled = 0;
+  int fetchSongsCalled = 0;
+
+  @override
+  Future<void> fetchArtists() async {
+    fetchArtistsCalled++;
+  }
+
+  @override
+  Future<void> fetchAlbums() async {
+    fetchAlbumsCalled++;
+  }
+
+  @override
+  Future<void> fetchSongs() async {
+    fetchSongsCalled++;
+  }
+}
+
+void main() {
+  group('init', () {
+    MockMusicDataRepository mockMusicDataRepository;
+
+    setUp(() {
+      mockMusicDataRepository = MockMusicDataRepository();
+    });
+
+    test(
+      'should fetch artists, albums and songs from the database',
+      () async {
+        // arrange
+        final MockInitMusicDataStore mockInitMusicDataStore =
+            MockInitMusicDataStore(
+                musicDataRepository: mockMusicDataRepository);
+
+        // act
+        mockInitMusicDataStore.init();
+
+        // assert
+        expect(mockInitMusicDataStore.fetchArtistsCalled, 1);
+        expect(mockInitMusicDataStore.fetchAlbumsCalled, 1);
+        expect(mockInitMusicDataStore.fetchSongsCalled, 1);
+      },
+    );
+
+    test(
+      'should only fetch data once',
+      () async {
+        // arrange
+        final MockInitMusicDataStore mockInitMusicDataStore =
+            MockInitMusicDataStore(
+                musicDataRepository: mockMusicDataRepository);
+
+        // act
+        mockInitMusicDataStore.init();
+        mockInitMusicDataStore.init();
+
+        // assert
+        expect(mockInitMusicDataStore.fetchArtistsCalled, 1);
+        expect(mockInitMusicDataStore.fetchAlbumsCalled, 1);
+        expect(mockInitMusicDataStore.fetchSongsCalled, 1);
+      },
+    );
+  });
+
+  group('fetchArtists', () {
+    MockMusicDataRepository mockMusicDataRepository;
+    const List<Artist> artists = [
+      Artist(name: 'AC/DC'),
+      Artist(name: 'Amon Amarth'),
+    ];
+
+    const Either<Failure, List<Artist>> success =
+        Right<Failure, List<Artist>>(artists);
+
+    final Either<Failure, List<Artist>> failure = Left(GenericFailure());
+
+    setUp(() {
+      mockMusicDataRepository = MockMusicDataRepository();
+    });
+
+    test(
+      'should store a list of artists on success',
+      () async {
+        // arrange
+        when(mockMusicDataRepository.getArtists())
+            .thenAnswer((_) => Future.value(success));
+
+        final musicDataStore = MusicDataStore(musicDataRepository: mockMusicDataRepository);
+
+        // act
+        await musicDataStore.fetchArtists();
+
+        // assert
+        expect(musicDataStore.artists.toList(), artists);
+      },
+    );
+
+    test(
+      'should store an empty list of artists on failure',
+      () async {
+        // arrange
+        when(mockMusicDataRepository.getArtists())
+            .thenAnswer((_) => Future.value(failure));
+
+        final musicDataStore = MusicDataStore(musicDataRepository: mockMusicDataRepository);
+
+        // act
+        await musicDataStore.fetchArtists();
+
+        // assert
+        expect(musicDataStore.artists.toList(), []);
+      },
+    );
+  });
+}