无法在 Angular2 测试中运行服务(从文档中粘贴的代码副本)

Question

我有以下错误(单元测试Angular2)：

当测试模块已经实例化。确保您以前没有使用injectTestBed.configureTestingModule

这是我的代码(它基本上是从angular文档中复制粘贴的)，它抛出了上面的错误：

import { TestBed, async } from '@angular/core/testing';
import { By } from '@angular/platform-browser';
import { AppModule } from './app.module';
import { AppComponent } from './app.component'
import { MyServiceService } from './my-service.service'
beforeEach(() => {
// stub UserService for test purposes
let userServiceStub = {
isLoggedIn: true,
user: { name: 'Test User'}
};
TestBed.configureTestingModule({
declarations: [ AppComponent],
providers:    [ {provide: MyServiceService, useValue: userServiceStub } ]
});
let fixture = TestBed.createComponent(AppComponent);
let comp    = fixture.componentInstance;
// UserService from the root injector
let userService = TestBed.get(MyServiceService);
//  get the "welcome" element by CSS selector (e.g., by class name)
let de = fixture.debugElement.query(By.css('.nesto'));
let el = de.nativeElement;
it('should welcome "Bubba"', () => {
userService.user.name = 'something'; // welcome message hasn't been shown yet
fixture.detectChanges();
expect(el.textContent).toContain('some');
});
});

我想经营一项服务，但似乎我就是做不到。

Answer 1

最可能的问题是您试图在beforeEach()中运行测试。您需要确保所有it()方法都在beforeEach():之外/之后

beforeEach(() => {
// stub UserService for test purposes
let userServiceStub = {
isLoggedIn: true,
user: { name: 'Test User'}
};
TestBed.configureTestingModule({
declarations: [ AppComponent],
providers:    [ {provide: MyServiceService, useValue: userServiceStub } ]
});
let fixture = TestBed.createComponent(AppComponent);
let comp    = fixture.componentInstance;
// get the "welcome" element by CSS selector (e.g., by class name)
let de = fixture.debugElement.query(By.css('.nesto'));
let el = de.nativeElement;
});

it('should welcome "Bubba"', inject([MyServiceService], (userService) => {
userService.user.name = 'something'; // welcome message hasn't been shown yet
fixture.detectChanges();
expect(el.textContent).toContain('some');
}));

Answer 2

这很有效，删除了beforeEach()中的实例并注入到it()中。

所有学分归Z.Bagley 所有

import { TestBed, async, inject } from '@angular/core/testing';
import { By } from '@angular/platform-browser';
import { AppModule } from './app.module';
import { AppComponent } from './app.component'
import { MyServiceService } from './my-service.service'
import { Inject } from '@angular/core';
beforeEach(() => {
// stub UserService for test purposes
let userServiceStub = {
isLoggedIn: true,
user: { name: 'Test User'}
};
TestBed.configureTestingModule({
declarations: [ AppComponent],
providers:    [ {provide: MyServiceService, useValue: userServiceStub } ]
});
});
it('should welcome "Bubba"', inject([MyServiceService], (userService) => {
let fixture=TestBed.createComponent(AppComponent);
fixture.detectChanges();
expect(userService.user.name).toContain('se');
}));