使用 Karma 进行 Angular 单元测试，测试分支或 serviceSpy () 出错

Question

I am currently testing an angular application in Angular 7, but I can't figure out how to test this branch of the submit function, I have approximately more 20 tests in this component, and some of them even use the same service spy as the test that isn't working:

The branch:

submit(): void {

    if (this.systemTable) {
      // this.formArray = this.formBuilder.array([]);
      while (this.formArray.length) {
        this.formArray.removeAt(0);
        console.log('dfdfdf');
      } //this.formArray.removeAt(0);


    } //...

My test:

it('submit() should remove when systemTable is true', () => {
    app.ngOnInit();

    app.systemTable = true; //Entering the branch i wan't to test

    const f = app.formArray; 
    app.addRow(); //This function adds a row into the app.formRow, I checked it's values with a debugger and it's working
    const userServiceSpy = spyOn(app.formArray, 'removeAt');

    app.submit();
    expect(userServiceSpy).toHaveBeenCalledTimes(1);
  });

Answer 1

将循环从 while 更改为 for，在 angular 8 中将不再需要此循环。