Firebase Storage Test (Attempt)

app_code.dart

// boring app code ...

Future<dynamic> thefuntion() async {
  
  final thumbnailFile = File('some/path');
    
          final uploadThumbnailTask = _storage
            .ref('thumbnails/1234/something')
            .putFile(thumbnailFile);
        final uploadThumbnailSnapshot =
            await uploadThumbnailTask.whenComplete(() => null);
        final thumbnailURL = await uploadThumbnailSnapshot.ref.getDownloadURL();

}
// ...

firebase_storage_test.dart

class MockFirestore extends Mock implements FirebaseFirestore {}

class MockCollectionReference extends Mock implements CollectionReference {}

class MockDocumentReference extends Mock implements DocumentReference {}

class MockDocumentSnapshot extends Mock implements DocumentSnapshot {}

class MockFirestorage extends Mock implements FirebaseStorage {}

class MockStorageReference extends Mock implements Reference {}

class MockTaskSnapshot extends Mock implements TaskSnapshot {}

class MockUploadTask extends Mock implements UploadTask {}


void main() {
  MockFirestore _firestore;
  MockDocumentSnapshot mockDocumentSnapshot;
  MockCollectionReference mockCollectionReference;
  MockDocumentReference mockDocumentReference;

  MockFirestorage _storage;
  MockStorageReference _storageReference;
  MockTaskSnapshot _taskSnapshot;
  MockUploadTask _uploadTask;


  setUp(() {
    _firestore = MockFirestore();
    _storage = MockFirestorage();

    mockCollectionReference = MockCollectionReference();
    mockDocumentReference = MockDocumentReference();
    mockDocumentSnapshot = MockDocumentSnapshot();

    _storageReference = MockStorageReference();
    _taskSnapshot = MockTaskSnapshot();
    _uploadTask = MockUploadTask();

  });

  test(
      'given test',
      () async {
    final getDataMap = <String, dynamic>{
      'tasks': [
        {'title': 'task A', 'photos': []},
        {'title': 'task B', 'photos': []}
      ]
    };
    when(_firestore.collection(any)).thenReturn(mockCollectionReference);
    when(mockCollectionReference.doc(any)).thenReturn(mockDocumentReference);
    when(mockDocumentReference.get())
        .thenAnswer((_) async => mockDocumentSnapshot);
    when(mockDocumentSnapshot.data()).thenReturn(getDataMap);
    when(mockDocumentReference.set(any, any)).thenAnswer((_) async => {});

    when(_storage.ref(any)).thenReturn(_storageReference);
    when(_storageReference.putFile(any, any)).thenAnswer((_) => _uploadTask);
    when(_storageReference.putFile(any)).thenAnswer((_) => _uploadTask);

    when(_uploadTask.then(any)).thenAnswer((_) async => _taskSnapshot);
    when(_uploadTask.whenComplete(any)).thenAnswer((_) async => _taskSnapshot);

    when(_taskSnapshot.ref).thenReturn(_storageReference);

    when(_storageReference.getDownloadURL()).thenAnswer((_) async => 'url');

        
    final response = await thefuntion();

    response.fold(
      (l) => fail('test should not return failure. Failure: $l'),
      (r) => expect(r, unit),
    );
  });