Angular2 NgModel在Jasmine测试中未获得值

Question

<form id="createWorkout" #cwf="ngForm" (ngSubmit)="showWorkout(skillCountFld)" novalidate>
  <input name="skillCount" id="skillCount" class="form-control" #skillCountFld="ngModel" ngModel />
  <button type="submit" id="buildWorkout">Build a Workout</button>
</form>

组件如下：

import { Component, OnInit } from '@angular/core';
import {SkillService} from "../model/skill-service";
import {NgModel} from "@angular/forms";

@Component({
  selector: 'app-startworkout',
  templateUrl: './startworkout.component.html',
  styleUrls: ['./startworkout.component.css']
})
export class StartworkoutComponent implements OnInit {
  public skillCount:String;

  constructor(public skillService:SkillService) { }

  showWorkout(value:NgModel):void {
    console.log('breakpoint', value.value);
  }

  ngOnInit() {
  }

}

以下是规范：

/* tslint:disable:no-unused-variable */
import {async, ComponentFixture, TestBed, fakeAsync, tick} from '@angular/core/testing';
import {By, BrowserModule} from '@angular/platform-browser';
import { DebugElement } from '@angular/core';

import { StartworkoutComponent } from './startworkout.component';
import {SkillService} from "../model/skill-service";
import {Store} from "../core/store";
import {SportService} from "../model/sport-service";
import {FormsModule} from "@angular/forms";
import {dispatchEvent} from "@angular/platform-browser/testing/browser_util";

describe('StartworkoutComponent', () => {
  let component: StartworkoutComponent;
  let fixture: ComponentFixture;
  let element:DebugElement;
  let skillService:SkillService;

  beforeEach(async(() => {
    var storeSpy:any = jasmine.createSpyObj('store', ['getValue', 'storeValue', 'removeValue']);
    var stubSkillService:SkillService = new SkillService(storeSpy);
    TestBed.configureTestingModule({
      declarations: [ StartworkoutComponent ],
      providers: [{provide:Store , useValue:storeSpy}, SportService, SkillService],
      imports: [BrowserModule, FormsModule]
    })
    .compileComponents();
  }));

  beforeEach(() => {
    fixture = TestBed.createComponent(StartworkoutComponent);
    component = fixture.componentInstance;
    element = fixture.debugElement;
    fixture.detectChanges();

  });

  it('should create', () => {
    expect(component).toBeTruthy();
  });

  describe('without workout', () => {
    let createWorkout:DebugElement;
    let skillCount:HTMLInputElement;
    let submitButton:HTMLButtonElement;
    beforeEach(() => {
      createWorkout = element.query(By.css('#createWorkout'));
      skillCount = element.query(By.css('#skillCount')).nativeElement;
      submitButton = element.query(By.css('#buildWorkout')).nativeElement;
    });
    it('has createWorkout form', () => {
      expect(createWorkout).toBeTruthy();
      expect(skillCount).toBeTruthy();
    });
    it('submits the value', fakeAsync(() => {
      spyOn(component, 'showWorkout').and.callThrough();
      tick();
      skillCount.value = '10';
      dispatchEvent(skillCount, 'input');
      fixture.detectChanges();
      tick(50);
      submitButton.click();
      fixture.detectChanges();
      tick(50);
      expect(component.showWorkout).toHaveBeenCalledWith('10');
    }));
  });
});

我肯定我错过了一些基本的/简单的东西，但我花了过去一天的时间梳理了所有我能找到的东西，没有运气。

<p>{{cwf.value | json}}</p>

Answer 1

Angular站点上有大量测试成功地设置了此设置，而无需等待何时稳定https://github.com/Angular/Angular/blob/874243279d5fd2bef567a13e0cef8d0cdf68eec1/modules/%40Angular/forms/test/template_integration_spec.ts#l1043

这是因为这些测试中的所有代码都是在fakeasync区域内执行的，而您在beforeach内激发fixture.detectChanges（）；。因此fakeasync区域不知道其作用域之外的异步操作。当您调用DetectChanges时，第一次初始化NGModel

 NgModel.prototype.ngOnChanges = function (changes) {
            this._checkForErrors();
            if (!this._registered)
                this._setUpControl(); //<== here

并获取输入事件的正确回调

NgForm.prototype.addControl = function (dir) {
  var _this = this;
  resolvedPromise.then(function () { // notice async operation
      var container = _this._findContainer(dir.path);
      dir._control = (container.registerControl(dir.name, dir.control));
      setUpControl(dir.control, dir); // <== here

在SetupControl中，可以看到Input事件将调用的函数

dir.valueAccessor.registerOnChange(function (newValue) {
  dir.viewToModelUpdate(newValue);
  control.markAsDirty();
  control.setValue(newValue, { emitModelToViewChange: false });
});

1）因此，如果您将fixture.detectchanges从beforeace移动到您的测试中，那么它应该可以工作：

 it('submits the value', fakeAsync(() => {
   spyOn(component, 'showWorkout').and.callThrough();
   fixture.detectChanges();

   skillCount = element.query(By.css('#skillCount')).nativeElement;
   submitButton = element.query(By.css('#buildWorkout')).nativeElement;

   tick();
   skillCount.value = '10';
   dispatchEvent(skillCount, 'input');
   fixture.detectChanges();

   submitButton.click();
   fixture.detectChanges();
   expect(component.showWorkout).toHaveBeenCalledWith('10');
}));

但是这个解决方案似乎非常复杂，因为您需要重写代码来移动每个it语句中的fixture.detectchanges（skillcount、submitbutton等也有问题）

2）正如Dinistro所说的，async和whenstable也可以帮助您：

it('submits the value', async(() => {
  spyOn(component, 'showWorkout').and.callThrough();
  fixture.whenStable().then(() => {
    skillCount.value = '10';
    dispatchEvent(skillCount, 'input');
    fixture.detectChanges();

    submitButton.click();
    fixture.detectChanges();

    expect(component.showWorkout).toHaveBeenCalledWith('10');
  })
}));

柱塞实例

但是等等，为什么我们要改变我们的代码？

3）只需将async添加到beforeEach函数中

beforeEach(async(() => {
  fixture = TestBed.createComponent(StartworkoutComponent);
  component = fixture.componentInstance;
  element = fixture.debugElement;
  fixture.detectChanges();
}));

柱塞实例