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。angular 4.3.0在执行异步函数后调用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。