[英]Testing a simple service that uses .next, .subscribe in Angular 4 using Karma / Jasmin
I have a simple service in my app like so... 我的应用程式中有一项简单的服务,就像这样...
import {Injectable} from '@angular/core';
import {Observable} from 'rxjs/Observable';
import {Subject} from 'rxjs/Subject';
@Injectable()
export class WizardDialogNavigationService {
public navAction$: Observable<any>;
private navActionSubject: Subject<any> = new Subject();
constructor() {
this.navAction$ = this.navActionSubject.asObservable();
}
public navAction(action: string): void {
this.navActionSubject.next(action);
}
}
It's not the most complex service, it just allows me to communicate between components. 它不是最复杂的服务,它只允许我在组件之间进行通信。 Now I need to test it, I have to admit I know very little about testing.
现在我需要测试,我不得不承认我对测试了解甚少。 I just want to check that when
WizardDialogNavigationService.navAction
is called the navAction$
Observable contains the passed string, so I wrote the following... 我只是想检查,当
WizardDialogNavigationService.navAction
被称为navAction$
可观察包含传递的字符串,所以我写了下面...
import {TestBed, inject, async} from '@angular/core/testing';
import {Observable} from 'rxjs/Rx';
import {expect} from 'chai';
import * as sinon from 'sinon';
import {WizardDialogNavigationService} from './wizard-dialog-navigation.service';
describe('WizardDialogNavigationService', () => {
beforeEach(() => {
TestBed.configureTestingModule({
providers: [WizardDialogNavigationService]
});
})
describe('navAction$ Observable', () => {
let sut: WizardDialogNavigationService; // sut = Service Under Test
beforeEach(inject([WizardDialogNavigationService], (service: WizardDialogNavigationService) => {
sut = service;
}));
it('should be the last passed value', async(() => {
const resultList = [];
sut.navAction('TestString');
sut.navAction$.subscribe((result) => resultList.push(result));
console.log(resultList); // output is []
expect(resultList.indexOf('TestString')).to.equal(0);
}));
});
});
I think I am going about this wrong as the resultList array doesn't contain the passed value? 我想我要解决这个错误,因为resultList数组不包含传递的值? It's as if the
.next() .subscribe()
isn't being called / ran. 好像
.next() .subscribe()
未被调用/运行。 If anyone can tell me where I am going wrong I would appreciate it. 如果有人能告诉我我要去哪里错,我将不胜感激。
You need a BehaviorSubject
which will return the already stored value, if you subscribe
to it directly. 如果直接
subscribe
,则需要一个BehaviorSubject
,它将返回已存储的值。
So you can change the Subject
to a BehaviorSubject
and subscribe to it and it will work. 因此,您可以将
Subject
更改为BehaviorSubject
并订阅它,它将起作用。
Doc: 文件:
https://github.com/ReactiveX/rxjs/blob/master/doc/subject.md#behaviorsubject https://github.com/ReactiveX/rxjs/blob/master/doc/subject.md#behaviorsubject
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