错误状态：在 `when()` 中未调用 Mock 方法。是否调用了真正的方法？答案

【问题标题】：Bad state: Mock method was not called within `when()`. Was a real method called?错误状态：在 `when()` 中未调用 Mock 方法。是否调用了真正的方法？
【发布时间】：2019-08-20 19:35:40
【问题描述】：

我正在尝试使用 mockito 在颤振中模拟 httpRequest。

这里我定义了一个全局http客户端：

library utgard.globals;

import 'package:http/http.dart' as http;

http.Client httpClient = http.Client();

然后我在集成测试中替换：

import 'package:flutter_driver/driver_extension.dart';
import 'package:http/http.dart' as http;
import 'package:utgard/globals.dart' as globals;
import 'package:mockito/mockito.dart';

import 'package:utgard/main.dart' as app;

class MockClient extends Mock implements http.Client {}

void main() {
  final MockClient client = MockClient();
  globals.httpClient = client;

  enableFlutterDriverExtension();

  app.main();
}

然后我尝试使用 when 的 mockito：

test('login with correct password', () async {
      final client = MockClient();

      when(globals.httpClient.post('http://www.google.com'))
          .thenAnswer((_) async => http.Response('{"title": "Test"}', 200));

      await driver.enterText('000000');
      await driver.tap(loginContinuePasswordButton);
    });

但我收到以下错误：

错误状态：未在 when() 内调用模拟方法。是否调用了真正的方法？

【问题讨论】：

标签： dart flutter mockito flutter-test

【解决方案1】：

我找到的解决方案是在 test_driver/app.dart 中定义 mock，然后调用 runApp 函数，这样即使在 Flutter 集成测试中也可以应用 mock： p>

import 'package:flutter/widgets.dart';
import 'package:flutter_driver/driver_extension.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:utgard/business/config/globals.dart';
import 'package:utgard/main.dart' as app;

class MockClient extends Mock implements http.Client {}

void main() {
  enableFlutterDriverExtension();

  final MockClient client = MockClient();
  // make your mocks here
  httpClient = client;

  runApp(app.MyApp());
}

因为它可以变成一个巨大的代码来模拟所有的请求，你可以创建一个单独的函数来更好地组织代码：

import 'package:flutter/widgets.dart';
import 'package:flutter_driver/driver_extension.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:utgard/business/config/globals.dart';
import 'package:utgard/main.dart' as app;

class MockClient extends Mock implements http.Client {}

void main() {
  enableFlutterDriverExtension();

  final MockClient client = MockClient();
  makeMock();
  httpClient = client;

  runApp(app.MyApp());
}

【讨论】：

【解决方案2】：

当您实现要模拟的方法而不是让 Mockito 执行该操作时，可能会发生此问题。

下面这段代码将返回Bad state: Mock method was not called within when(). Was a real method called?:

class MockFirebaseAuth extends Mock implements FirebaseAuth {
  FirebaseUser _currentUser;

  MockFirebaseAuth(this._currentUser);

  // This method causes the issue.
  Future<FirebaseUser> currentUser() async {
    return _currentUser;
  }
}

final user = MockFirebaseUser();
final mockFirebaseAuth = MockFirebaseAuth(user);

// Will throw `Bad state: Mock method was not called within `when()`. Was a real method called?`
when(mockFirebaseAuth.currentUser())
    .thenAnswer((_) => Future.value(user));

你想要的是：

class MockFirebaseAuth extends Mock implements FirebaseAuth {}

final user = MockFirebaseUser();
final mockFirebaseAuth = MockFirebaseAuth();

// Will work as expected
when(mockFirebaseAuth.currentUser())
    .thenAnswer((_) => Future.value(user));

当您尝试在非模拟子类上调用 when() 时也会发生此问题：

class MyClass {
  String doSomething() {
    return 'test';
  }
}

final myClassInstance = MyClass();

// Will throw `Bad state: Mock method was not called within `when()`. Was a real method called?`
when(myClassInstance.doSomething())
    .thenReturn((_) => 'mockedValue');

【讨论】：

在我的例子中，我想模拟 toString()，这样我可以更清楚地看到错误，不仅仅是类名，而且 toString() 已经从 Mock 本身定义。

【解决方案3】：

还有一种可能。如果您的模拟对象发生这种情况，那么它可能已经过时了。在这种情况下，请尝试使用

重新生成模拟对象

flutter pub run build_runner build --delete-conflicting-outputs

【讨论】：