angular 4.3.0在执行异步函数后调用fixture.whenStable

Question

我正在为一个应用程序编写jasmine/karma/webpack单元测试，其中有许多内部承诺在代码中深入解析。我想使用角度的异步，fixture.detectChanges和fixture.whenStable。

作为一个概念证明，我做了以下简单但非常异步的组件。

import {Component} from "@angular/core"; 
import {Logger} from "../../utils/logger"; 

@Component({ 
    selector: 'unit-test.html', 
    template: `  
    <div class="unit-test"> 
    <h3>Unit Test Component</h3> 
    <h4>p1: {{p1}}</h4> 
    <h4>v1: {{v1}}</h4> 
    <h4>p2: {{p2}}</h4> 
    <h4>v2: {{v2}}</h4> 
    <h4>p3: {{p3}}</h4> 
    <h4>v3: {{v3}}</h4> 
    </div>` 
}) 
export class UnitTestComponent { 
    p1: Promise<string>; 
    v1: string; 
    p2: Promise<string>; 
    v2: string; 
    p3: Promise<string>; 
    v3: string; 

    constructor() { 
    this.p1 = makeTimeoutPromise('value1', 2000); 
    Logger.warn('p1 created'); 
    this.p1.then(data => { 
     this.v1 = data 
    }); 
    } 

    method2() { 
    this.p2 = makeTimeoutPromise('value2', 2000); 
    this.p2.then(data => { 
     this.v2 = data 
    }); 
    Logger.warn('p2 created'); 
    } 

    method3() { 
    this.p3 = makeTimeoutPromise('value3', 2000); 
    this.p3.then(data => { 
     this.v3 = data 
    }); 
    Logger.warn('p2 created'); 
    } 
} 


function makeTimeoutPromise(result: string, timeout: number) { 
    return new Promise<string>((resolve, reject) => { 
    setTimeout(() => { 
     resolve(result); 
     Logger.warn(`resolved '${result}' after '${timeout}' seconds`); 
    }, timeout) 
    }); 
} 

为了测试这个，我在异步块中创建了组件。这是有效的，并且在构造函数的承诺解决之后，它会开始运行。

在测试内部，我调用comp.method2（），它导致承诺在2秒后解决。然而......这里是我没有得到的部分......在调用comp.method2（）后立即调用fixture.isStable（）返回true。我本来预计会错误的。更糟.... fixture.whenStable（）立即解析。由于实际方法中的承诺尚未解决，我还没有想要测试的价值。

import {UnitTestComponent} from './unit-test.component'; 
import {async, ComponentFixture, TestBed, tick} from '@angular/core/testing'; 
import {DebugElement} from '@angular/core'; 

describe('UnitTestComponent',() => { 
    let de: DebugElement; 
    let comp: UnitTestComponent; 
    let fixture: ComponentFixture<UnitTestComponent>; 
    let el: HTMLElement; 
    const startTime = Date.now(); 
    beforeEach(async(() => { 
    console.log('time beforeEach.start', Date.now() - startTime); 
    const testbed = TestBed.configureTestingModule({ 
     declarations:[UnitTestComponent], 
     imports: [], 
     providers: [] 
    }); 
    // testbed.compileComponents(); 
    console.log('time beforeEach.initSsmpComponentLibModule', Date.now() - startTime); 
    fixture = TestBed.createComponent(UnitTestComponent); 
    comp = fixture.componentInstance; 
    de = fixture.debugElement; 
    console.log('time beforeEach.end', Date.now() - startTime); 
    })); 

    it('should create the component', async(() => { 
    // const x = new Promise<any>((resolve, reject)=>{ 
    // setTimeout(()=>{ 
    //  console.log('right before exit', comp); 
    //  fixture.detectChanges(); 
    //  resolve(); 
    //  }, 10000); 
    // }); 
    console.log('time it.start', Date.now() - startTime, comp); 
    expect(comp).toBeDefined(); 
    console.log('fixture.isStable() (1)', fixture.isStable()); 
    comp.method2(); 
    console.log('fixture.isStable() (2)', fixture.isStable()); 
    fixture.whenStable() 
     .then(data=>{ 
     fixture.detectChanges(); 
     console.log('time after whenStable(1) resolves', Date.now() - startTime, comp); 
     fixture.detectChanges(); 
     console.log('time after whenStable(1).detect changes completes', Date.now() - startTime, comp); 
     expect(comp.v2).toBe('value2'); 
     comp.method3(); 
     console.log('method3 called', Date.now() - startTime, comp); 
     fixture.detectChanges(); 
     console.log('time after detectChanges (2)', Date.now() - startTime, comp); 
     fixture.whenStable() 
      .then(data=>{ 
      fixture.detectChanges(); 
      console.log('time after whenStable(3).then', Date.now() - startTime, comp); 
      expect(comp.v3).toBe('value3'); 
      }); 
     console.log('time after whenStable(3)', Date.now() - startTime, comp); 

     }); 
    console.log('time after whenStable(2)', Date.now() - startTime, comp); 
    })); 


}); 

控制台日志输出如下。我期待

fixture.isStable() (2) false 
time after whenStable(2) >=4386 UnitTestComponent {p1: ZoneAwarePromise, v1: "value1", p2: ZoneAwarePromise} 

，但得到

fixture.isStable() (2) true 
time after whenStable(2) 2390 UnitTestComponent {p1: ZoneAwarePromise, v1: "value1", p2: ZoneAwarePromise} 

---

time beforeEach.start 363 
time beforeEach.initSsmpComponentLibModule 363 
time beforeEach.end 387 
time it.start 2386 UnitTestComponent {p1: ZoneAwarePromise, v1: "value1"} 
fixture.isStable() (1) true 
fixture.isStable() (2) true 
time after whenStable(2) 2390 UnitTestComponent {p1: ZoneAwarePromise, v1: "value1", p2: ZoneAwarePromise} 
time after whenStable(1) resolves 2393 time beforeEach.start 363 

没有comp.method2的显性知识（）的内部，我怎么能有角等到所有的承诺从解决方法在里面调用它（）方法？我认为这是fixture.whenStable的明确作用。

Answer 1

回答我自己的问题。当然！我没有在一个区域中跑步。所以有两种方法可以解决这个问题。 （我证明了两者）。

解决方案1：获取本地元素并单击它.....如果您正在测试浏览器事件。 （所以我添加使用

const button = de.query(By.css('#unit-test-method-2-button')); 
expect(button).toBeDefined(); 
button.nativeElement.click(); 

的我需要更好的解决方案是简单地注入NgZone

<button id='unit-test-method-2-button'(click)="method2()">Method 2</button> 

然后叫方法2（）。这让我做嵌套调用fixture.whenStable（ ）。

因此我加

beforeEach(inject([NgZone], (injectedNgZone: NgZone) => { 
    ngZone = injectedNgZone; 
})); 

这让我打电话给异步方法2，一d然后异步method3，并使用fixture.whenStable ...

it('should create the component', async(() => { 
    ngZone.run(() => { 
    console.log('time it.start', Date.now() - startTime, comp); 
    expect(comp).toBeDefined(); 
    expect(fixture.isStable()).toBe(true, 'expect fixture to be stable'); 
    comp.method2(); 
    expect(fixture.isStable()).toBe(false, 'expect fixture not to be stable'); 
    fixture.whenStable() 
     .then(data => { 
     fixture.detectChanges(); 
     expect(comp.v2).toBe('value2'); 
     comp.method3(); 
     fixture.whenStable() 
      .then(data => { 
      fixture.detectChanges(); 
      expect(comp.v3).toBe('value3'); 
      }); 
     }); 
    }); 
}));