如何使用Jasmine测试多个顺序调用 [英] How to test multiple sequential calls with Jasmine

问题描述

我正在尝试测试一个取消所有订阅退订的功能:

I am trying to test a function that unsubscribes from all subscriptions:

ngOnDestroy() {
        this.tryUnsubscribe(this.carsSubscription);
        this.tryUnsubscribe(this.partsSubscription);
        this.tryUnsubscribe(this.shopsSubscription);
    }

这是我为此功能编写的测试:

This is the test I wrote for the function:

it('should unsubscribe from subscriptions ', () => { 
      spyOn(component, "tryUnsubscribe");     
      component.ngOnDestroy();
      expect(component.tryUnsubscribe).toHaveBeenCalledWith(component['carsSubscription']);
      expect(component.tryUnsubscribe).toHaveBeenCalledWith(component['partsSubscription']);
      expect(component.tryUnsubscribe).toHaveBeenCalledWith(component['shopsSubscription']);
    });

问题:

如果我注释掉一个函数调用，则测试仍会通过.

If I comment out a function call, the tests still passes.

ngOnDestroy() {
        this.tryUnsubscribe(this.carsSubscription);
        //this.tryUnsubscribe(this.partsSubscription);
        this.tryUnsubscribe(this.shopsSubscription);
    }

仅当我注释掉所有这些函数调用时，测试才会失败:

Only if I comment out all of these function calls, the test fails:

ngOnDestroy() {
        //this.tryUnsubscribe(this.carsSubscription);
        //this.tryUnsubscribe(this.partsSubscription);
        //this.tryUnsubscribe(this.shopsSubscription);
    }

如何正确测试这种功能?我在做什么错了?

How to properly test this kind of function? What am I doing wrong?

推荐答案

我会将您的测试重写为以下内容:

I would rewrite your test to the following:

it('should unsubscribe from subscriptions ', () => { 
  const spy = spyOn(component, 'tryUnsubscribe');     
  component.ngOnDestroy();

  // Check how many times the spy was called
  expect(spy).toHaveBeenCalledTimes(3);
});

如果现在取消注释tryUnsubscribe调用之一，则测试将失败，因为间谍仅被调用了两次.

If you now uncomment one of the tryUnsubscribe calls, the test should fail as the spy was only called twice.

另一种方法是模拟订阅，或者只是将它们设置为虚拟值，以测试ngDestroy tryUnsubscribe内部是否使用了这三个组件变量:

Another approach would be to mock the subscriptions or just set them to a dummy value to test that inside the ngDestroy tryUnsubscribe was called with those 3 component variables:

it('test unsubscribing', () => {
  // Mock values
  component.carsSubscription = Observable.of(1).subscribe(() => {});
  component.partsSubscription = Observable.of(1).subscribe(() => {});
  component.shopsSubscription = Observable.of(1).subscribe(() => {});

  const spy = spyOn(component, 'tryUnsubscribe').and.callThrough();     
  component.ngOnDestroy();

  // Check how many times the spy was called
  expect(spy).toHaveBeenCalledTimes(3);

  // Check arguments
  expect(spy.calls.all()[0].args[0]).toEqual(component.carsSubscription);
  expect(spy.calls.all()[1].args[0]).toEqual(component.partsSubscription);
  expect(spy.calls.all()[2].args[0]).toEqual(component.shopsSubscription);
});

此处 是该测试的一项有效工作.

Here is a working stackblitz with the test.

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