test: Is there a way to test between 2 cubit that communicate on parent cubit?

[masfranzhuo]

Description

So, I have 2 cubits: CategoryCubit and ProductCubit. Then I added one cubit on top of that. It working fine, but just can't fond a way to test it.

Here the code:

class CategoryCubit extends Cubit<CategoryState> {
  CategoryCubit() : super(const CategoryState.initial());

  void selectCategory({required CategoryEntity category}) async {
    if (state is Loaded) {
      emit(CategoryState.loaded(selectedCategory: category));
    }
  }
}

class ProductCubit extends Cubit<ProductState> {
  ProductCubit({required FetchProducts fetchProducts})
      : _fetchProducts = fetchProducts,
        super(const ProductState.initial());

  final FetchProducts _fetchProducts;

  Future<void> fetchProducts({
    String? categoryId,
    int limit = 10,
    int page = 1,
    String? searchText,
  }) async {
    emit(const Loading());

    final result = await _fetchProducts(
      categoryId: categoryId,
      limit: limit,
      page: page,
      searchText: searchText,
    );
    result.fold(
      (error) => emit(Error(error: error)),
      (products) => emit(Loaded(products: products.data)),
    );
  }
}

class CategoryProductIntegrationCubit extends Cubit<CategoryProductIntegrationState> {
  final product.ProductCubit productCubit;
  final category.CategoryCubit categoryCubit;

  late StreamSubscription categoryStreamSubscription;

  CategoryProductIntegrationCubit({
    required this.productCubit,
    required this.categoryCubit,
  }) : super(const _Initial()) {
    categoryStreamSubscription = categoryCubit.stream.listen((state) {
      if (state is category.Loaded) {
        if (state.selectedCategory != null) {
          productCubit.fetchProducts(categoryId: state.selectedCategory!.id);
        }
      }
    });
  }
}

[felangel]

Hi @masfranzhuo 👋
Thanks for opening an issue!

You can test the CategoryProductIntegrationCubit by injecting a MockCubit for productCubit and categoryCubit respectively. Then you can stub the categoryCubit stream using whenListen from package:bloc_test and verify that productCubit.fetchProducts is called with the correct id.

Hope that helps!

[masfranzhuo]

Hi @masfranzhuo 👋 Thanks for opening an issue!

You can test the CategoryProductIntegrationCubit by injecting a MockCubit for productCubit and categoryCubit respectively. Then you can stub the categoryCubit stream using whenListen from package:bloc_test and verify that productCubit.fetchProducts is called with the correct id.

Hope that helps!

Hello @felangel , I have tried the approach and found error when running the test, is something I do wrong?

void main() {
  late CategoryProductIntegrationCubit cubit;
  late MockProductCubit mockProductCubit;
  late MockCategoryCubit mockCategoryCubit;

  setUp(() {
    mockProductCubit = MockProductCubit();
    mockCategoryCubit = MockCategoryCubit();

    cubit = CategoryProductIntegrationCubit(
      productCubit: mockProductCubit,
      categoryCubit: mockCategoryCubit,
    );
  });

  test('emits _Initial state initially', () {
    expect(cubit.state, const CategoryProductIntegrationState.initial());
  });

  test('should verify fetch product, when category changes', () {
    whenListen(
      mockCategoryCubit,
      Stream.fromIterable(
        [
          const CategoryState.loaded(categories: []),
          const CategoryState.loaded(
            selectedCategory: CategoryEntity(id: 'anyId', name: 'anyName'),
            categories: [],
          ),
        ],
      ),
    );

    cubit.categoryCubit.selectCategory(
      category: const CategoryEntity(id: 'anyId', name: 'anyName'),
    );

    verify(() => mockProductCubit.fetchProducts(categoryId: 'anyId'));
  });
}

the error in console:

No matching calls (actually, no calls at all).
(If you called `verify(...).called(0);`, please instead use `verifyNever(...);`.)
package:test_api                                                                                                              fail

[felangel]

Hi @masfranzhuo 👋
Sounds like you're running into something similar to felangel/mocktail#204. If you're still having trouble could you please share a link to a minimal reproduction sample and I'm happy to take a closer look, thanks! 🙏