如何使用 Jasmine 测试多个顺序调用

Question

我正在尝试测试一个取消订阅所有订阅的函数：

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

这是我为该函数编写的测试：

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，测试仍然通过。

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

只有当我注释掉所有这些函数调用时，测试才会失败：

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

如何正确测试这种功能？我究竟做错了什么？

Answer 1

我会将您的测试重写为以下内容：

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

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

如果您现在取消对其中一个tryUnsubscribe调用的注释，则测试应该会失败，因为 spy 只被调用了两次。

另一种方法是模拟订阅，或者只是将它们设置为一个虚拟值来测试ngDestroy tryUnsubscribe使用这 3 个组件变量调用的内部：

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);
});

这 是测试的有效堆栈闪电战。

Answer 2

还可以使用 Jasmine Calls.allArgs() 方法一次检查所有参数：

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expect(spy.calls.allArgs()).toEqual([\n  [component.carsSubscription],\n  [component.partsSubscription],\n  [component.shopsSubscription]\n]);\n

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这是修改后的 Fabian K\xc3\xbcng\ 在 stackblitz 中的答案。

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