如何使用Injector模拟功能中的注入服务

时间:2019-03-31 19:57:08

标签: angular unit-testing jasmine karma-runner

在Angular 7.x中,我有一个全局错误处理程序,可以通过Injector注入其服务。因此,每个函数都有与注入器的引用,如下所示:

import { ErrorHandler, Injectable, Injector, NgZone } from '@angular/core';
import { Router } from '@angular/router';
import { LoggingService } from '../logging/logging.service';
import { EnvironmentService } from '../services/environment.service';

@Injectable()
export class GlobalErrorHandler implements ErrorHandler {
  constructor(private readonly injector: Injector, private readonly zone: NgZone) {}

  handleError(error: any): void {
    // Handle Client Error (Angular Error, ReferenceError...)
    this.processError(error);

    throw error;
  }

  processError(error: any): void {
    const environmentService = this.injector.get(EnvironmentService);
    const environment = environmentService.getEnvironment();
    if (!environment.production) {
      console.error(error);
    } else {
      // Log the expection to the logger
      this.logException(error);

      this.zone.run(() => {
        this.navigateToErrorPage(error);
      });
    }
  }

  private logException(error: any): void {
    const loggingService = this.injector.get(LoggingService);
    loggingService.logException(error);
  }

  private navigateToErrorPage(error: any): void {
    const router = this.injector.get(Router);
    router.navigate(['/500'], { queryParams: { error } });
  }
}

如您所见,在processError函数中,我注入了环境服务。该服务的唯一目标是能够在我的规格测试中模拟环境。我在另一个服务测试中执行此操作,但是我将其与依赖项注入一起使用,而不是与this.injector.get(...)函数一起使用。

有人知道我是怎么嘲笑这个的吗?

it('should log the error if the environment is in production', () => {
  // Arrange
  const environmentSpy = jasmine.createSpyObj('EnvironmentService', 'getEnvironment'); ??? How do I mock this ???

  const error: Error = new Error('New Error');
  spyOn<any>(errorHandler, 'logException');
  // Act
  errorHandler.processError(error);

  // Assert
  expect(errorHandler['logException']).toHaveBeenCalledWith(error);
});

1 个答案:

答案 0 :(得分:0)

您可以监视Injector并返回伪造的类,以代替具有自定义getEnvironment()方法的EnvironmentService:

spyOn(TestBed.get(Injector), 'get').and.callFake((token) => {
    if (token === EnvironmentService) {
        // Return a mocked EnvironmentService class
        return {
            getEnvironment: () => { return { production: true }; }
        };
    } else {
        // Otherwise, return whatever was originally defined in the TestBed
        return TestBed.get(token);
    }
});

或者,您可以使用真实的Injector并在EnvironmentService上进行监视:

spyOn(TestBed.get(EnvironmentService), 'getEnvironment').and
    .returnValue({ production: true });