Erro de karma - nenhum navegador capturado, abra http: // localhost: 9876 /

Comecei a usar o Karma pela primeira vez ... Seguindo este tutorial:https://angular.io/docs/ts/latest/guide/testing.html Estou escrevendo um teste simples para verificar se o título está correto. Eu sempre entendo issoerror: "Nenhum navegador capturado, abertohttp: // localhost: 9876 /" .Estou usando Angular 2 e texto datilografado. Estas são as versões

"@angular/core": "2.4.10" 
"jasmine-core": "^2.6.2",
"karma": "^1.7.0".

Minha estrutura de pastas fica assim

mydashboard
 -src
   -app
     -welcome
       -welcome.component.ts
       -welcome.component.spec.ts   
 -karma.conf.js

//karma.conf.js
module.exports = function(config) {
  config.set({
    basePath: '',
    frameworks: ['jasmine'],
    files: ["src/app/**/*.spec.ts"
    ],
    exclude: [
    ],
    preprocessors: {
    },
    reporters: ['progress'],
    port: 9876,
    colors: true,
    logLevel: config.LOG_INFO,
    autoWatch: true,
    browsers: ['Chrome'],
    singleRun: false,
    concurrency: Infinity
  })
}
//welcome.component.spec.ts
import { ComponentFixture, TestBed } from '@angular/core/testing';
import { By }              from '@angular/platform-browser';
import { DebugElement }    from '@angular/core';
import { WelcomeComponent } from './welcome.component';

describe('WelcomeComponent  (inline template)', () => {
  let comp:    WelcomeComponent;
  let fixture: ComponentFixture<WelcomeComponent>;
  let de:      DebugElement;
  let el:      HTMLElement;
  beforeEach(() => {
    TestBed.configureTestingModule({
      declarations: [ WelcomeComponent  ], // declare the test component
    });
    fixture = TestBed.createComponent(WelcomeComponent);
    comp = fixture.componentInstance; // WelcomeComponent  test instance
    // query for the title <h1> by CSS element selector
    de = fixture.debugElement.query(By.css('h1'));
    el = de.nativeElement;
  });

  it('should display original title', () => {
  fixture.detectChanges();
  expect(el.textContent).toContain(comp.title);
});
});
//welcome.component.ts
import { Component } from '@angular/core';
@Component({
  template: '<h1>{{title}}</h1>'
})
export class WelcomeComponent {
  title = 'Test Tour of Heroes';
}

questionAnswers(1)

yourAnswerToTheQuestion