使用 jasmine、jest 或 ts-mockito 模拟类的构造函数

Question

我有一组类以这种方式接收角度之外的一些依赖项。

import {TypeATest} from '...../TypeA.model'
import { TypeBTest } from '..../TypeB.model'
import { SomeDependency } from './services/SomeDependency'
import { SomeAnother } from './services/SomeAnother'
  // ....

@Injectable({
  providedIn: 'root'
})
export class TestingService {
  this.activeTest: AnyTestType;

  constructor(private readonly injectorService: InjectorService) {}

  loadTest(TypeOfTest) {
    const someDependency = this.injectorService.get(SomeDependency)
    const someAnother = this.injectorService.get(SomeAnother)
      switch(TypeOfTest) {
        case TypeA:
            injector
            this.activeTest = new TypeATest(someDependency, someAnother);
            break;
        case TypeB:
            this.activeTest = new TypeBTest(someAnother);
            break;
      }
  }

  startTest(){
    this.activeTest.start()
  }

// .. more this.activeTest uses...
}

我正在对加载该外部类的服务进行单元测试，但我不想创建 TypeATest、TypeBTest 或类似的，而只是模拟结果（它们都有相同的 API）但我找不到如何嘲笑他们。有没有办法做到这一点？

Answer 1

这两个构造函数是它们各自模块的命名导出。

您可以使用带有模块工厂的jest.mock 模拟整个模块：

jest.mock('...../TypeA.model', () => {
  const start = jest.fn();
  const result = { start };
  return jest.fn(() => result);  
});

test('something', () => {
  // ...
});

...或仅使用jest.spyOn模拟模块的命名导出：

import * as TypeB from '..../TypeB.model';

test('something', () => {
  const spy = jest.spyOn(TypeB, 'TypeBTest');
  const start = jest.fn();
  spy.mockReturnValue({ start });
  // ...
})