Question

我第一次运行“ ng测试”并收到此错误：

src / app / _directives / head-title.directive.spec.ts（5,23）中的错误：错误TS2554：预期有2个参数，但得到0。

由于spec.ts文件是由Angular自动生成的，所以我不知道该怎么做...

这是我的指令：

import { Directive, ElementRef, AfterContentInit  } from '@angular/core';
import { Title } from '@angular/platform-browser';

@Directive({
  selector: '[edHeadTitle]'
})

export class HeadTitleDirective implements AfterContentInit{

  constructor(private el: ElementRef,private titleService: Title) {}

  ngAfterContentInit(){
    this.titleService.setTitle(this.el.nativeElement.innerHTML);
  }

}

这是对应的规范：

import { HeadTitleDirective } from './head-title.directive';

describe('HeadTitleDirective', () => {
  it('should create an instance', () => {
    const directive = new HeadTitleDirective();
    expect(directive).toBeTruthy();
  });
});

显然，令人讨厌的部分是“ new HeadTitleDirective（）”……我想应该有一些参数，但是哪些以及如何？

package.json中的版本信息：

"devDependencies": {
    "@angular-devkit/build-angular": "~0.6.8",
    "@angular/cli": "~6.0.8",
    "@angular/compiler-cli": "^6.0.6",
    "@angular/language-service": "^6.0.6",
    "@types/jasmine": "~2.8.6",
    "@types/jasminewd2": "~2.0.3",
    "@types/node": "~8.9.4",
    "codelyzer": "~4.2.1",
    "jasmine-core": "~2.99.1",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "~1.7.1",
    "karma-chrome-launcher": "~2.2.0",
    "karma-coverage-istanbul-reporter": "~2.0.0",
    "karma-jasmine": "~1.1.1",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~5.3.0",
    "ts-node": "~5.0.1",
    "tslint": "~5.9.1",
    "typescript": "~2.7.2"
  }

Answer 1

这是基本编码。

这是您的班级签名：

constructor(private el: ElementRef,private titleService: Title) {}

创建方式如下：

const directive = new HeadTitleDirective();

您在那使用这个问题吗？

要解决此问题，只需创建依赖项的模拟即可。

let elRefMock = {
  nativeElement: document.createElement('div')
};

let serviceMock = {
  setTitle: (title: string) => null
};

const directive = new HeadTitleDirective(elRefMock, serviceMock);

Answer 2

我也不完全理解为什么会发生此错误，但是可以通过在您的specs.ts中直接将指令类型设置为指令const来工作

import { HeadTitleDirective } from './head-title.directive';

describe('HeadTitleDirective', () => {
  it('should create an instance', () => {
    const directive = HeadTitleDirective;
    expect(directive).toBeTruthy();
  });
});

* .directive.spec.ts中的错误TS2554

2 个答案: