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Question

在测试时如何模拟子组件？我有一个父组件调用,product-selected其模板如下所示:

<section id="selected-container" class="container-fluid">
    <hr/>
  <product-settings></product-settings>
  <product-editor></product-editor>
  <product-options></product-options>
</section>

组件声明如下所示:

import { Component, Input }               from '@angular/core'; 

import { ProductSettingsComponent } from '../settings/product-settings.component';                                      
import { ProductEditorComponent }   from '../editor/product-editor.component';                                      
import { ProductOptionsComponent }  from '../options/product-options.component';                                        

@Component({
    selector: 'product-selected',
    templateUrl: './product-selected.component.html',
    styleUrls: ['./product-selected.component.scss']
})
export class ProductSelectedComponent {}

这个组件实际上只是其他组件所在的位置,可能不包含任何其他功能.

但是当我设置测试时,我得到以下模板错误,对所有三个组件重复:

Error: Template parse errors:
    'product-editor' is not a known element:
    1. If 'product-editor' is an Angular component, then verify that it is part of this module.
    2. If 'product-editor' is a Web Component then add "CUSTOM_ELEMENTS_SCHEMA" to the '@NgModule.schemas' of this component to suppress this message. ("
        <hr/>
      <product-settings></product-settings>
      [ERROR ->]<product-editor></product-editor>

我试图加载一个模拟版本的子组件但不知道该怎么做 - 我见过的例子只是覆盖了父组件,甚至没有提到子组件.那我该怎么做呢？

Answer 1

小心一点NO_ERRORS_SCHEMA.让我们引用相同文档的另一部分:

使用NO_ERRORS_SCHEMA进行浅组件测试可大大简化复杂模板的单元测试.但是,编译器不再警告您错误,例如拼写错误或误用的组件和指令.

我发现这个缺点与编写测试的目的完全相反.更重要的是,模拟基本组件并不难.

这里尚未提到的方法只是在配置时声明它们:

@Component({
  selector: 'product-settings',
  template: '<p>Mock Product Settings Component</p>'
})
class MockProductSettingsComponent {}

@Component({
  selector: 'product-editor',
  template: '<p>Mock Product Editor Component</p>'
})
class MockProductEditorComponent {}

...  // third one

beforeEach(() => {
  TestBed.configureTestingModule({
      declarations: [
        ProductSelectedComponent,
        MockProductSettingsComponent,
        MockProductEditorComponent,
        // ... third one
      ],
      providers: [/* your providers */]
  });
  // ... carry on
});

Answer 2

找到了一个近乎完美的解决方案,如果有人重构某个组件,它也会正确地抛出错误.

npm install --only=dev ng-mocks

现在你的.spec.ts就可以了

import { MockComponent } from 'ng-mocks';
import { ChildComponent } from './child.component.ts';
...
  beforeEach(
async(() => {
  TestBed.configureTestingModule({
    imports: [FormsModule, ReactiveFormsModule, RouterTestingModule],
    declarations: [
      ComponentUnderTest,
      MockComponent(ChildComponent),
      ...

这将创建一个新的匿名组件,它具有与ChildComponent相同的选择器,@ Input()和@Output()属性,但没有附加代码.

假设您的ChildComponent有一个@Input() childValue: number绑定在被测组件中的,<app-child-component [childValue]="inputValue" />

唯一的缺点到目前为止,我已经找到了,就是,你不能使用By.directive(ChildComponent)你的测试中,作为类型的变化,而是你可以使用By.css('app-child-component')像这样

it('sets the right value on the child component`, ()=> {
     component.inputValue=5;
     fixture.detectChanges();
     const element = fixture.debugElement.query(By.css('app-child-component'));
     expect(element).toBeTruthy();

     const child: ChildComponent = element.componentInstance;

     expect(child.childValue).toBe(5);
});

Answer 3

通常,如果您在组件的视图中使用了一个正在测试的组件,并且您根本不想声明这些组件,因为它们可能有自己的依赖关系,以避免**某些东西不是已知元素:**错误您应该使用NO_ERRORS_SCHEMA.

import { NO_ERRORS_SCHEMA }          from '@angular/core';

TestBed.configureTestingModule({
        declarations: declarations,
        providers: providers
        schemas:      [ NO_ERRORS_SCHEMA ]
  })

基于文档:

将NO_ERRORS_SCHEMA添加到测试模块的模式元数据中,以告知编译器忽略无法识别的元素和属性.您不再需要声明不相关的组件和指令.

更多相关信息:https://angular.io/docs/ts/latest/guide/testing.html#!#shallow-component-test

Answer 4

我发布了这个问题所以我可以发布一个答案,因为我挣扎了一两天.这是你如何做到的:

let declarations = [
  ProductSelectedComponent,
  ProductSettingsComponent,
  ProductEditorComponent,
  ProductOptionsComponent
];

beforeEach(() => {
        TestBed.configureTestingModule({
            declarations: declarations,
            providers: providers
        })
        .overrideComponent(ProductSettingsComponent, {
            set: {
                selector: 'product-settings',
                template: `<h6>Product Settings</h6>`
            }
        })
        .overrideComponent(ProductEditorComponent, {
            set: {
                selector: 'product-editor',
                template: `<h6>Product Editor</h6>`
            }
        })
        .overrideComponent(ProductOptionsComponent, {
            set: {
                selector: 'product-options',
                template: `<h6>Product Options</h6>`
            }
        });

        fixture = TestBed.createComponent(ProductSelectedComponent);
        cmp = fixture.componentInstance;
        de = fixture.debugElement.query(By.css('section'));
        el = de.nativeElement;
    });

您必须overrideComponent为每个子组件链接函数.