Angular Jest 测试`找不到名称'By'。`

Question

我将 Jest.JS 与 Angular 一起使用。当我尝试测试指令时，出现错误：

Cannot find name 'By'.

src/app/directives/error-highlighter.directive.spec.ts:33:46 - error TS2304: Cannot find name 'By'.

    33         inputEl = fixture.debugElement.query(By.css('input'));

用我的node_module - 安装东西需要什么？

directive.spec 文件：

import { ErrorHighlighterDirective } from './error-highlighter.directive';
import { Directive, ElementRef, SimpleChanges, HostListener, Renderer2, Component, DebugElement } from '@angular/core';
import { NgControl, FormGroup, FormsModule, FormControl, ReactiveFormsModule } from '@angular/forms';
import { TestBed, ComponentFixture } from '@angular/core/testing';

@Component({
    template: `<input errorHighlighter formControlName="Url" type="text">`
})
class TestHighlighterComponent { }



describe('ErrorHighlighterDirective', () => {

    let component: TestHighlighterComponent;
    let fixture: ComponentFixture<TestHighlighterComponent>;
    let inputEl: DebugElement;

    const fg: FormGroup = new FormGroup({
        'Url': new FormControl('')
    });

    beforeEach(() => {
        TestBed.configureTestingModule({
            declarations: [TestHighlighterComponent, ErrorHighlighterDirective],
            imports: [FormsModule, ReactiveFormsModule],
            providers: [
                { provide: NgControl, useValue: fg }
            ]
        });
        fixture = TestBed.createComponent(TestHighlighterComponent);
        component = fixture.componentInstance;
        inputEl = fixture.debugElement.query(By.css('input'));

    });


    it('should create an instance', () => {
        const directive = new ErrorHighlighterDirective(inputEl, fg, Renderer2);
        expect(directive).toBeTruthy();
    });

});

Answer 1

你需要从 angular.platform-b​​rowser 导入 By

import { By } from '@angular/platform-browser'

您可以进一步阅读here。