How to mock Riverpod's Reader? - flutter

Question

I have the following repository and I'd like to test it. I know this may be a silly question but I'm still learning.
class AuthRepository implements AuthBaseRepository {
final Reader _read;
const AuthRepository(this._read);
#override
Future<User> login({String email, String password}) async {
try {
final response = await _read(dioProvider).post(
'/sign_in',
data: {
"user": {
"email": email,
"password": password,
},
},
);
return _mapUserFromResponse(response);
} on DioError catch (_) {
throw const CustomException(message: 'Invalid login credentials.');
} on SocketException catch (_) {
const message = 'Please check your connection.';
throw const CustomException(message: message);
}
}
And this is what I've done so far:
void main() {
test('loadUser', () async {
Dio dio;
DioAdapterMockito dioAdapterMockito;
AuthRepository repository;
setUpAll(() {
dio = Dio();
dioAdapterMockito = DioAdapterMockito();
dio.httpClientAdapter = dioAdapterMockito;
repository = AuthRepository(_reader_here_);
});
test('mocks any request/response via fetch method', () async {
final responsePayload =
await parseJsonFromAssets("assets/api-response.json");
final responseBody = ResponseBody.fromString(
responsePayload,
200,
headers: {
Headers.contentTypeHeader: [Headers.jsonContentType],
},
);
when(dioAdapterMockito.fetch(any, any, any))
.thenAnswer((_) async => responseBody);
});
});
}
I have no idea of how to mock Reader. Basically, I've seen something like class MyMock extends Mock implements Something but Reader is not a class, it's a function so I'm completely lost.
Any help/tips/examples will be appreciated.
Thanks in advance!

Answer 1

Instead of trying to mock a Reader, create a provider for your repository and use ProviderContainer to read it.
class AuthRepository implements AuthBaseRepository {
const AuthRepository(this._read);
static final provider = Provider<AuthRepository>((ref) => AuthRepository(ref.read));
final Reader _read;
#override
Future<User> login({String email, String password}) async {
...
}
Example usage:
final user = createTestUser();
final container = ProviderContainer(
overrides: [
// Example of how you can mock providers
dio.overrideWithProvider(mockDio),
],
);
final repo = container.read(AuthRepository.provider);
expectLater(
await repo.login(email: 'AzureDiamond', password: 'hunter2'),
user,
);
You could also consider using the overrides in ProviderContainer to mock Dio instead of involving a mocking framework to simplify your tests further.
More on testing here.