flutter 中的单元测试 firebase 抛出异常“未创建 Firebase 应用程序‘[DEFAULT]’ - 调用 Firebase.initializeApp()”

Question

I need to unit test an application that uses firebase. My unit tests always says "Unhandled Exception: [core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()". I absolutely understand why this problem occurs. But I still want to unit test my methods without really starting firebase. Even Mocking the firebase stuff did not help. Hopefully you can help me out? What am I misunderstanding?

For Example I rewrote the code from this tutorial: https://www.youtube.com/watch?v=4d6hEaUVvuU

This is my test class: ("Auth" Class in YT example is "Authentification" in my code)

import 'package:firebase_auth/firebase_auth.dart';
import 'package:hrw_textscanner/firebase/Authentification.dart';
import 'package:mockito/mockito.dart';
import 'package:test/test.dart';

class MockUser extends Mock implements User {}

final MockUser _mockUser = MockUser();

class MockFirebaseAuth extends Mock implements FirebaseAuth {
  @override
  Stream<User> authStateChanges() {
    return Stream.fromIterable([
      _mockUser,
    ]);
  }
}

void main() {
  final MockFirebaseAuth mockFirebaseAuth = new MockFirebaseAuth();
  final Authentification authentification =
      new Authentification(mockFirebaseAuth);

  test("emit occurs", () async {
    expectLater(authentification.authStateChanges, emitsInOrder([_mockUser])); //authStateChanges is the same as "user" in example
  });
}

In the Example in Youtube it works - my code still leads into that error mentioned above :(