Mocking dependencies | Dependency Injection Issues

[JuanxCursed]

Hi guys!
I'm working on my firsts tests with flutter so, if I state something wrong please do not consider has a bad thing, but as an opportunity to learn more about it.

I'm trying to mock a function but I'm not able to do it.

What I expect
When I mock a class/method I expect to return the mocked values (even intercepting a dependency inside another method)

What happens
The mock is completed ignored and the class Users is instantiated and responds from the server instead of the mock. (Which make sense, but is not what I want at test level)

I'm trying to figure out the right way to proceed with these tests when working with this kind of "global" injection.

Here is how I'm "get more close" of an actual real world result:

login_controller_test.dart

@GenerateMocks([UsersUtil])
void main() {
  TestWidgetsFlutterBinding.ensureInitialized();
  initModule(LoginModule());
  LoginController login;
  MockUsersUtil users;

  setUp(() async {
    login = LoginModule.to.get<LoginController>();
    users = MockUsersUtil();
  });

  group('LoginController Test:', () {
    test("Validate instance", () {
      expect(login, isInstanceOf<LoginController>());
    });

    test('Must return a string list with emails', () async {
      when(users.userList()).thenReturn(['b@b.com']);
      List<String> user = login.getBetaListIfActive(t);
      expect(user.length, 1);
      expect(user[0], 'b@b.com');
    });
  });
}

A fake class just for testing purposes (this values come from an configuration API)
FAKE user.dart

class UsersUtil {
  List<String> userList() {
    return ['a@a.com'];
  }
}

login_controller.dart

abstract class _LoginControllerBase with Store {
  @action
  Future login() async {
    loading = true;
    try {
      List<String> betaUsers = getBetaListIfActive();
      ...
     }
   }

  ...
  List<String> getBetaListIfActive() {
    Users t = UsersUtil(); // Instead here comes our service
    List<String> users = t.userList();
    return users;
  }
}

Thanks everyone o/

[jacobaraujo7]

Check this

[JuanxCursed]

Hey @jacobaraujo7, thanks for the response.
I refactored all the app dependencies injection to "respect" the modular pattern (https://modular.flutterando.com.br/docs/flutter_modular/dependency-injection), but now my `UserUtil' which is injected on AppModule file is not being found.
I did a search about that and did not find anything useful to fix it.

I'm using modular at 2.0.1

My UserUtil is sync but depends on async other classes to be instantiated, this can cause any issues? Please, ignore the SS below code, is used just to give a full context of his dependencies

[jacobaraujo7]

Your bind cannot be asynchronous. Consider using AsyncBind.

[JuanxCursed]

Hi @jacobaraujo7 , thanks for the assistance.
Unfortunately looks like AsyncBind is not working as I expected, or there is missing on the Docs/My setup.

This is my app_module.dart:

$StorageUtil:

my AppGuard:

This is the error that I got:

I've tried to create another "async bind class" class to make the prop isLazy as false, but I got exact the same issue.

PS: It's not even trying to start the SplashModule

[UPDATE]

Guys, new findings here. I was working on a brand new clean project to debug properly and discovery this:

When we set isLazy to false on StorageUtil everything breaks and I get an exception of BindNotFound (BindNotFound: SharedPreferences) cause "SharedPreferences" is not loaded yet. (What I expect to be loaded since we use AsyncBind)

When is set to true and you use a "post module" AppModule (async instance here) > Home Module (use StorageUtil here) everything works fine with StorageUtil class

BUT! When we use any class that depends on StorageUtil like UserUtil the injection is not happening leading to the prop storageUtil of UserUtil as null

I must be missing something really stupid here to this not work as expected.

[mayroncachina]

I have exactly this problem...

[dehypnosis]

Same here... related issue.
It seems like AsyncBind won't resolve dependent Bind objects when module.isReady called.

[marcguilera]

I am facing the same issue. Let me know if we may be missing something or this is how it works.

If it's how it works, it does seem like undesirable behaviour as it is not what the consumer would expect.

In my opinion, this limits the modularity possibilities greatly as we may have:
StorageModule (AsyncBind) -> SomeOtherModule -> AppModule.

As the writer of AppModule I would like to call Modular.isModuleReady and have all dependencies working (I shouldn't need to know that StorageModule even exists).

[jacobaraujo7]

Hello.
When the module is ready, it turns asynchronous binds into synchronous ones. So in mock you can do it directly as a synchronous Bind.

Hope this helps.
Anyway, open this issue to continue the thread.