[英]Angular 9 + jest : unit test, mock a promise and check method called then
我需要帮助,我不知道如何模拟 Promise 并检查 then() 部分中调用的方法。
当我单击表单的保存按钮时,我的代码如下所示:
// File : myComponent.ts
save() {
const myObject = new MyObject({field: this.form.value.field});
this.myService.saveObject(myObject).then(() => { // I'd like to mock this
this.closeDialog(true);
}, error => {
this.otherFunction(error);
});
}
// File : myService.ts
saveOject(myObject: MyObject): Promise<any> {
return this.myApi.save(myOject).toPromise().then(res => res);
}
// File : myApi.ts
save(myObject: MyObject) {
return this.http.post('url, myObject);
}
我正在尝试测试这个函数,我想模拟(或存根?我不知道有什么区别)saveObject 函数,当承诺得到解决时,情况并非如此。
我的实际测试文件如下所示:
describe('MyComponent', () => {
let component: MyComponent;
let fixture: ComponentFixture<MyComponent>;
let myService: MyService;
beforeEach(async (() => {
TestBed.configureTestingModule(
).compileComponents();
myService = TestBed.inject(MyService);
}
beforeEach(() => {
fixture = TestBed.createComponent(MyComponent);
component = fixture.componentInstance;
fixture.detectChanges();
spyOn(myService, 'saveOject').and.returnValue(new Promise(resolve => resolve()));
});
it('should call closeDialog method when save form is successful', () => {
const spyCloseDialog = jest.spyOn(component, 'closeDialog');
component.save();
fixture.detectChanges(); // It's a test, I don't know if it's useful
expect(spyCloseDialog).toHaveBeenCalledTimes(1); // It's 0 because I don't know how to be in the then part of my function
});
}
有人可以帮助我吗? 真挚地
有两个选项可供选择:
1)使用fakeAsync ,例如:
it('should call closeDialog method when save form is successful', fakeAsync(() => {
const spyCloseDialog = jest.spyOn(component, 'closeDialog');
component.save();
tick(50);
expect(spyCloseDialog).toHaveBeenCalledTimes(1);
}));
2)把你的expect
放在里面then
,例如
component.save().then(() => expect(spyCloseDialog).toHaveBeenCalledTimes(1));
在您的测试中,您应该导入HttpClientTestingModule
,以便测试成功运行并且在 angular 尝试启动 http 调用时不会引发错误。
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