如何在服务中对事件发射器进行单元测试
如何在服务中对事件发射器进行单元测试
提问于 2021-07-08 17:03:39
我有一个名为EmitterService的服务，如下所示。
import { Injectable, EventEmitter } from '@angular/core';
@Injectable()
export class EmitterService {
public helpDisplayEmitter: EventEmitter<string> = new EventEmitter();我已经将该服务注入到构造函数中的一个组件中。我有一个名为getHelpDisplay()的方法，在那里我将值发送到发射器。
export class MainPageComponent implements OnInit, OnChanges {
constructor(public emitter: EmitterService) { }
getHelpDisplay(helpItem: any) {
this.helpValue = helpItem;
this.emitter.helpDisplayEmitter.emit(this.helpValue);
}
}我想为这个发射器写一个单元测试用例，但是我得到了错误，请帮我解决这个问题。
等级库文件
describe('MainpageComponent', () => {
let component: MainPageComponent;
let fixture: ComponentFixture<MainPageComponent>;
let mainpage, element, de;
beforeEach(() => {
TestBed.configureTestingModule({
imports: [],
providers: [MainPageComponent, EmitterService]
});
});
it('should emit false via createCustomer$ from breadCrumbService', inject([EmitterService], (service: EmitterService) => {
fixture = TestBed.createComponent(MainPageComponent);
mainpage = fixture.componentInstance;
mainpage.getHelpDisplay("helpItem");
expect(service.helpDisplayEmitter.emit).toHaveBeenCalledWith("helpItem");
}));我得到了下面的错误...
Error: <toHaveBeenCalledWith> : Expected a spy, but got Function.
Usage: expect(<spyObj>).toHaveBeenCalledWith(...arguments)
Error: <toHaveBeenCalledWith> : Expected a spy, but got Function.
Usage: expect(<spyObj>).toHaveBeenCalledWith(...arguments)
at <Jasmine>
at UserContext.<anonymous> (src/app/mainpage/main-page.component.spec.ts:54:45)
at TestBedRender3.execute (node_modules/@angular/core/__ivy_ngcc__/fesm2015/testing.js:1953:1)
at UserContext.<anonymous> (node_modules/@angular/core/__ivy_ngcc__/fesm2015/testing.js:2629:1)
at ZoneDelegate.invoke (node_modules/zone.js/dist/zone-evergreen.js:364:1)
at ProxyZoneSpec.push.QpwO.ProxyZoneSpec.onInvoke (node_modules/zone.js/dist/zone-testing.js:292:1)
at ZoneDelegate.invoke (node_modules/zone.js/dist/zone-evergreen.js:363:1)
at Zone.run (node_modules/zone.js/dist/zone-evergreen.js:123:1)
Chrome Headless 91.0.4472.124 (Windows 10): Executed 1 of 584 (1 FAILED) (0 secs / 0.559 secs)
Chrome Headless 91.0.4472.124 (Windows 10) MainpageComponent should emit false via createCustomer$ from breadCrumbService FAILED回答 1
Stack Overflow用户
发布于 2021-07-09 12:54:52
您没有监视service.helpDisplayEmitter.emit()方法。使用spyOn将间谍安装到现有对象上。
例如。
main-page.component.ts
import { Component } from '@angular/core';
import { EmitterService } from './emitter.service';
@Component({})
export class MainPageComponent {
helpValue;
constructor(public emitter: EmitterService) {}
getHelpDisplay(helpItem: any) {
this.helpValue = helpItem;
this.emitter.helpDisplayEmitter.emit(this.helpValue);
}
}emitter.service.ts
import { Injectable, EventEmitter } from '@angular/core';
@Injectable()
export class EmitterService {
public helpDisplayEmitter: EventEmitter<string> = new EventEmitter();
}main-page.component.test.ts
import { ComponentFixture, TestBed, inject } from '@angular/core/testing';
import { EmitterService } from './emitter.service';
import { MainPageComponent } from './main-page.component';
fdescribe('MainpageComponent', () => {
let component: MainPageComponent;
let fixture: ComponentFixture<MainPageComponent>;
beforeEach(() => {
TestBed.configureTestingModule({
declarations: [MainPageComponent],
providers: [EmitterService],
}).compileComponents();
});
it('should emit false via createCustomer$ from breadCrumbService', inject(
[EmitterService],
(service: EmitterService) => {
spyOn(service.helpDisplayEmitter, 'emit');
fixture = TestBed.createComponent(MainPageComponent);
component = fixture.componentInstance;
component.getHelpDisplay('helpItem');
expect(service.helpDisplayEmitter.emit).toHaveBeenCalledWith('helpItem');
}
));
});包版本：
"@angular/core": "~11.0.3",
"@angular/cli": "~11.0.3",页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/68298617
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