javascript - 在 Angular 2 的单元测试中模拟基类

Question

我正在尝试编写一个单元测试以查看是否调用了基类方法

这是基类

export abstract class Animal{
   protected eatFood() {
      console.log("EAT FOOD!")
   }
}

这是我要测试的类

export class Monkey extends Animal {
   onHungry(){
      this.eatFood();
   }
}

这里是测试

class MockAnimal {
  public eatFood() { 
    console.log("EAT MOCKED FOOD!");
  }
}

describe('Monkey', () => {
  beforeEach(() => {

    TestBed.configureTestingModule({
       declarations:[Monkey],
       providers: [
         { provide: Animal, useClass: MockAnimal }
       ]
    }
  });

  it('eat food when hungry', fakeAsync(() => {
    let fixture = TestBed.createComponent(Monkey);
    spyOn(fixture, 'eatFood');
    fixture.componentInstance.onHungry();
    expect(fixture.eatFood).toHaveBeenCalled();
  }));
}

我无法让单元测试运行这个 MockAnimal 类。这是怎么测试的？

Answer 1

TestBed 用于测试组件，就像在普通的 NgModule 中一样，您可以定义声明、导入、提供程序……但是您想要测试的是一个简单的类。在测试中你必须手动初始化它:

describe('Monkey', () => {
  it('eats if hungry', () => {
    const monkey = new Monkey();
    // spying will only work if 'eatFood' is public
    const eatFoodSpy = spyOn(monkey, 'eatFood');

    monkey.onHungry();

    expect(eatFoodSpy).toHaveBeenCalled();
  });
});