为角度“提供者”设置基本单元测试

Question

I'm looking to set up a basic unit test for my angular application, specifically an Ionic application. I'm using karma/jasmine using a preconfigured solution by the ionic team. The included sample unit tests passed, so I proceeded to write a new unit-test for my own provider.

Here's where I get into trouble because there's no real sample to reference on. So I just created a TestBed and put the minimum required components in as you'd do with your application. However everytime I run the unit test a rather vague and undescriptive error: Error: Illegal state: Could not load the summary for directive TestServiceProvider.

Error: Illegal state: Could not load the summary for directive TestServiceProvider.
            at syntaxError (webpack:///node_modules/@angular/compiler/esm5/compiler.js:486:21 <- karma-test-shim.js:66892:34)
            at CompileMetadataResolver.getDirectiveSummary (webpack:///node_modules/@angular/compiler/esm5/compiler.js:15085:0 <- karma-test-shim.js:81491:31)
            at JitCompiler.getComponentFactory (webpack:///node_modules/@angular/compiler/esm5/compiler.js:34301:25 <- karma-test-shim.js:100707:63)

Looking at the stack trace it looks like it's caused by a SyntaxError. Although I'm not sure what and why it is occurring. Any idea what is being done wrong in this example?

import { TestServiceProvider } from './test';
import { TestBed, TestModuleMetadata, async, ComponentFixture } from '@angular/core/testing';

describe('Test Service', () => {
  let component: TestServiceProvider;
  let fixture: ComponentFixture<TestServiceProvider>;

  beforeEach(async( () => {
    TestBed.configureTestingModule({
      providers: [TestServiceProvider]
    }).compileComponents;
  }));

  beforeEach( () => {
    fixture = TestBed.createComponent(TestServiceProvider);
    component = fixture.componentInstance;
  });

  it('should add numbers', () => {
    expect(1+1).toBe(2);
  });
});

import { Injectable } from '@angular/core';
import { Http } from '@angular/http';
import 'rxjs/add/operator/map';

/*
  Generated class for the TestServiceProvider provider.

  See https://angular.io/guide/dependency-injection for more info on providers
  and Angular DI.
*/
@Injectable()
export class TestServiceProvider {

  constructor() {
    console.log('Hello TestServiceProvider Provider');
  }

}

Answer 1

You do not need to create a component instance as we are just testing a service. Just inject it and test it in test specs. Below is the minimum code that you need to start testing.

import { TestServiceProvider } from './test';
import { TestBed, TestModuleMetadata, async, ComponentFixture } from '@angular/core/testing';

describe('Test Service', () => {
  let component: TestServiceProvider;
  let fixture: ComponentFixture<TestServiceProvider>;

  beforeEach(async( () => {
    TestBed.configureTestingModule({
      providers: [TestServiceProvider]
    });
  service = TestBed.inject(TestServiceProvider);
  }));


  it('should add numbers', () => {
    expect(1+1).toBe(2);
  });
});