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首页 > 解决方案 > 角度测试错误 - NullInjectorError：没有 TrimInputDirective 的提供者

javascript - 角度测试错误 - NullInjectorError：没有 TrimInputDirective 的提供者

问题描述

我创建了一个 Angular 指令，它使用 CSS 选择器在我的应用程序中自动修剪输入，看起来像这样......

import { Directive, HostListener, forwardRef } from '@angular/core';
import { DefaultValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';

export const TRIM_VALUE_ACCESSOR: any = {
  provide: NG_VALUE_ACCESSOR,
  useExisting: forwardRef(() => TrimInputDirective),
  multi: true
};

/**
 * The trim accessor for writing trimmed value and listening to changes that is
 * used by the {@link NgModel}, {@link FormControlDirective}, and
 * {@link FormControlName} directives.
 */
/* tslint:disable */
@Directive({
  selector: `
    input
    :not([type=checkbox])
    :not([type=radio])
    :not([type=password])
    :not([readonly])
    :not(.ng-trim-ignore)
    [formControlName],

    input
    :not([type=checkbox])
    :not([type=radio])
    :not([type=password])
    :not([readonly])
    :not(.ng-trim-ignore)
    [formControl],

    input
    :not([type=checkbox])
    :not([type=radio])
    :not([type=password])
    :not([readonly])
    :not(.ng-trim-ignore)
    [ngModel],

    textarea
    :not([readonly])
    :not(.ng-trim-ignore)
    [formControlName],

    textarea
    :not([readonly])
    :not(.ng-trim-ignore)
    [formControl],

    textarea
    :not([readonly])
    :not(.ng-trim-ignore)[ngModel],
    :not([readonly])
    :not(.ng-trim-ignore)
    [ngDefaultControl]'
  `,
  providers: [ TRIM_VALUE_ACCESSOR ]
})
/* tslint:enable */
export class TrimInputDirective extends DefaultValueAccessor {

  protected _onTouched: any;

  /**
   * ngOnChange - Lifecycle hook that is called when any data-bound property of a directive changes.
   * @param {string} val - trim value onChange.
   */
  @HostListener('input', ['$event.target.value'])
  public ngOnChange = (val: string) => {
    this.onChange(val.trim());
  }

  /**
   * applyTrim - trims the passed value
   * @param {string} val - passed value.
   */
  @HostListener('blur', ['$event.target.value'])
  public applyTrim(val: string) {
    this.writeValue(val.trim());
    this._onTouched();
  }

  /**
   * writeValue - trims the passed value
   * @param {any} value - passed  value.
   */
  public writeValue(value: any): void {
    if (typeof value === 'string') {
      value = value.trim();
    }

    super.writeValue(value);
  }

  /**
   * registerOnTouched Registers a callback function that should be called when the control receives a blur event.
   * @param {function} fn - The user information.
   */
  public registerOnTouched(fn: any): void {
    this._onTouched = fn;
  }
}

现在作为一名优秀的开发人员，我必须纠正一些单元测试......所以我开始将一个文件放在一起，这里是

import {Component} from '@angular/core';
import {async, ComponentFixture, TestBed} from '@angular/core/testing';
import {By} from '@angular/platform-browser';
import {TrimInputDirective} from './trim-input.directive';

import {expect} from 'chai';

@Component({
  selector: 'my-directive-test-component',
  template: ''
})
class TestComponent {
}

describe('Trim Directive', () => {
  let fixture: ComponentFixture<TestComponent>;
  let inputDebugElement: any;
  let directive: TrimInputDirective;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [
        TestComponent,
        TrimInputDirective
      ],
      providers: []
    }).overrideComponent(TestComponent, {
      set: {
        template: '<input type="text">'
      }
    }).compileComponents().then(() => {
      fixture = TestBed.createComponent(TestComponent);
      fixture.detectChanges();
      inputDebugElement = fixture.debugElement.query(By.css('input'));
      directive = inputDebugElement.injector.get(TrimInputDirective);
    });
  }));

  it('should trim the input', () => {
    directive.ngOnChange('     1234.56     ')
    expect('1234.56').to.be('1234.56'); // I know this isn't the correct test... I will amend this
  });
});

现在我希望运行我的测试以确保规范文件中的设置正确，但我收到以下错误：

HeadlessChrome 0.0.0 (Mac OS X 10.12.6) Trim Directive "before each" hook for "should trim the input" FAILED Uncaught (in promise): Error: StaticInjectorError(DynamicTestModule)[TrimInputDirective]:
StaticInjectorError(Platform: core)[ TrimInputDirective]：NullInjectorError：没有 TrimInputDirective 的提供者！错误：StaticInjectorError（DynamicTestModule）[TrimInputDirective]：

我不明白为什么会出现此错误，为什么必须提供指令？我不认为这是必要的，如果我必须提供我应该提供什么？提供实际指令不起作用/解决错误？我很困扰。如果有人能告诉我如何解决这个问题或我为什么得到它，我将不胜感激。

请注意，这是一个遗留的 Angular 应用程序，是在 AngularCLI 可用之前构建的。所以它有点不正统（例如它没有使用 Jasmin）。

标签： javascriptangularunit-testingangular-directiveangular-unit-test

解决方案

你必须在你的TestComponent类似这样的东西中提供指令

@Component({
  selector: 'my-directive-test-component',
  template: '',
  providers: [ TrimInputDirective ]
})
class TestComponent {
}

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