unit-testing - 在 Jasmine 中通过 @input 模拟父 FormGroup

Question

所以我有一个像这样的子组件

export class ChildComponent implements OnInit {

  @Input('parentForm')
  public parentForm: FormGroup;

  constructor(private fb: FormBuilder, private cd: ChangeDetectorRef) { }

  ngOnInit() {
    this.parentForm.addControl('newControl', <Some Control>);
  }
}

接下来我有一个像这样的准系统单元测试文件

describe('ChildComponent', () => {
  let component: ChildComponent;
  let fixture: ComponentFixture<ChildComponent>;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      imports: [ReactiveFormsModule, FormsModule],
      declarations: [ ChildComponent ],
      providers: [ FormBuilder, FormGroup ]
    })
    .compileComponents();
  }));

  beforeEach(inject([FormBuilder], (fb: FormBuilder) => {
    fixture = TestBed.createComponent(ChildComponent);
    component = fixture.componentInstance;
    component.parentForm = fb.group({});
    component.ngOnInit();
    fixture.detectChanges();
  }));

  fit('should be created', () => {
    expect(component).toBeTruthy();
  });
});

以前我遇到过 parentForm 未定义的问题，所以我尝试通过在 beforeEach 中注入(inject) FormBuilder 来自己构建它 component.parentForm = fb.group({}); .但是现在的问题是 karma/ Jasmine 找不到 FormBuilder
Cannot find name 'FormBuilder'.
我要做的就是在单元测试期间创建组件实例时尝试获取或模拟 parentForm，我需要它，因为我在 for each 期间调用 ngOnInit，因为它是一个新控件。

有任何想法吗。谢谢

Answer 1

我能够为 Reactive Form Parent <-> Child 组件设置成功的 Karma 规范测试。希望下面的示例将有助于指导您的设置。我已经从我的代码库中简化了尽可能多的代码，以专注于您要解决的核心问题。

父组件

父组件.html

...
<div [stepControl]="childFormGroup">
  <child-form-group [formGroup]="childFormGroup"></child-form-group>
</div>
...

父组件.ts

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup, Validators, FormControl } from '@angular/forms';

@Component({
  selector: 'form-parent',
  templateUrl: './parent.component.html',
  styleUrls: ['./parent.component.scss']
})
export class FormParentComponent implements OnInit {
  // childFormGroup will be available on the parent DOM
  // so we can inject it / pass it to the ChildFormComponent
  public childFormGroup : FormGroup;

  constructor(private _formBuilder: FormBuilder) {
    this.createForm();
  }

  private createForm() : void {
    this.childFormGroup = this._formBuilder.group({
      name:  ['Sample Name', Validators.required],
      email: ['', Validators.required]
    });
  }
}

子组件

child.component.html

...
<form [formGroup]="formGroup">
  <p>This is the childFormGroup</p>
  <br>

  <div>
    <input  placeholder="Name"
            formControlName="name"
            autocomplete="off">
  </div>

  <div>
    <input  placeholder="Email"
            formControlName="email"
            autocomplete="off">
  </div>
</form>
...

child.component.ts

import { Component, Input, Output, EventEmitter } from '@angular/core';
import { FormGroup } from '@angular/forms';

@Component({
  selector: 'child-form-group',
  templateUrl: './child.component.html',
  styleUrls: ['./child.component.scss'],
})
export class ChildFormComponent {
  // This declares an inherited model available to this component
  @Input() formGroup : FormGroup;

  constructor() { }

  /* There is no need to create the formGroup here
     hence no constructor method call or ngOnInit() hook...
     It will simply inherit the formGroup by passing it as an
     attribute on the DOM from parent.component.html
  */
}

child.component.spec.ts

import { async, ComponentFixture, TestBed, inject } from '@angular/core/testing';
import { CUSTOM_ELEMENTS_SCHEMA } from '@angular/core';
import { FormsModule, ReactiveFormsModule, FormGroup, FormBuilder, Validators } from '@angular/forms';

import { ChildFormComponent } from './child.component';

describe('ChildFormComponent', () => {
  let component: ChildFormComponent;
  let fixture: ComponentFixture<ChildFormComponent>;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      schemas: [
        CUSTOM_ELEMENTS_SCHEMA
      ],
      imports: [
        FormsModule,
        ReactiveFormsModule
      ],
      declarations: [
        ChildFormComponent
      ]
    })
    .compileComponents();
   }));

  beforeEach(inject([FormBuilder], (fb: FormBuilder) => {
    fixture = TestBed.createComponent(Step2Component);
    component = fixture.componentInstance;

    /* This is where we can simulate / test our component
       and pass in a value for formGroup where it would've otherwise
       required it from the parent
    */
    component.formGroup = fb.group({
      name:  ['Other Name', Validators.required],
      email: ['', Validators.required]
    });
    fixture.detectChanges();
  }));

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