Angular4 Karma测试报错：无法解析RequestOptions的所有参数

Hey there, let's get this error sorted out for you! The issue here is that RequestOptions from @angular/http has underlying dependencies that aren't being properly provided in your test configuration—TestBed can't figure out what it needs to instantiate RequestOptions correctly.

Here's how to fix it step by step:

1. Update your TestBed configuration #

You need to supply the required dependencies for Http and RequestOptions, usually using MockBackend and BaseRequestOptions (both part of @angular/http). Add these to your test's providers array:

import { async, ComponentFixture, TestBed, inject } from '@angular/core/testing';
import { ResetPasswordComponent } from './reset-password.component';
import { ConfigService } from './../config-service.service';
import { Http, Headers, ConnectionBackend, RequestOptions, MockBackend, BaseRequestOptions } from '@angular/http';

describe('ResetPasswordComponent', () => {
  let component: ResetPasswordComponent;
  let fixture: ComponentFixture<ResetPasswordComponent>;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [ ResetPasswordComponent ],
      providers: [
        ConfigService,
        // Provide mock backend and base request options to handle HTTP dependencies
        MockBackend,
        BaseRequestOptions,
        // Configure Http with mock dependencies using a factory
        {
          provide: Http,
          useFactory: (backend: ConnectionBackend, options: RequestOptions) => new Http(backend, options),
          deps: [MockBackend, BaseRequestOptions]
        },
        // Explicitly provide RequestOptions so TestBed can resolve its parameters
        RequestOptions
      ]
    })
    .compileComponents();
  }));

  // Rest of your test code...
});

Why this works: #

• RequestOptions' constructor accepts an optional BaseRequestOptions instance. By adding BaseRequestOptions to your providers, TestBed can resolve the missing parameter for RequestOptions.
• MockBackend lets you mock HTTP requests in tests, which is critical for isolating your component from real API calls.
• The factory provider for Http ensures it gets created with the mock backend and base options, which also ties into resolving RequestOptions correctly.

Quick sanity checks: #

• Double-check that you've imported MockBackend and BaseRequestOptions from @angular/http (I included those imports in the snippet above).
• If your component directly injects RequestOptions, confirm it's listed in the providers array of your TestBed config.

That should clear up the parameter resolution error for RequestOptions! Let me know if you hit any other bumps along the way.

内容的提问来源于stack exchange，提问作者hondvryer