要解决Angular 2单元测试的问题，可以按照以下步骤进行：

1. 安装所需的依赖项：

   npm install --save-dev karma jasmine @types/jasmine karma-jasmine karma-chrome-launcher karma-coverage-istanbul-reporter
   

2. 创建一个karma配置文件karma.conf.js，并配置所需的文件和插件：

   module.exports = function (config) {
     config.set({
       basePath: '',
       frameworks: ['jasmine', '@angular/cli'],
       plugins: [
         require('karma-jasmine'),
         require('karma-chrome-launcher'),
         require('karma-coverage-istanbul-reporter'),
         require('@angular/cli/plugins/karma')
       ],
       client: {
         clearContext: false // leave Jasmine Spec Runner output visible in browser
       },
       coverageIstanbulReporter: {
         reports: ['html', 'lcovonly'],
         fixWebpackSourcePaths: true
       },
       angularCli: {
         environment: 'dev'
       },
       reporters: ['progress', 'kjhtml', 'coverage-istanbul'],
       port: 9876,
       colors: true,
       logLevel: config.LOG_INFO,
       autoWatch: true,
       browsers: ['Chrome'],
       singleRun: false
     });
   };
   

3. 创建一个测试文件，例如app.component.spec.ts，并编写测试代码：

   import { async, ComponentFixture, TestBed } from '@angular/core/testing';
   import { AppComponent } from './app.component';
   
   describe('AppComponent', () => {
     let component: AppComponent;
     let fixture: ComponentFixture;
   
     beforeEach(async(() => {
       TestBed.configureTestingModule({
         declarations: [AppComponent]
       })
         .compileComponents();
     }));
   
     beforeEach(() => {
       fixture = TestBed.createComponent(AppComponent);
       component = fixture.componentInstance;
       fixture.detectChanges();
     });
   
     it('should create the app', () => {
       expect(component).toBeTruthy();
     });
   
     it(`should have as title 'app'`, () => {
       expect(component.title).toEqual('app');
     });
   
     it('should render title in a h1 tag', () => {
       const compiled = fixture.debugElement.nativeElement;
       expect(compiled.querySelector('h1').textContent).toContain('Welcome to app!');
     });
   });
   

4. 在package.json文件中，添加一个test脚本来运行测试：

   "scripts": {
     "test": "ng test"
   }
   

5. 运行测试：

   npm test
   

这样，你就可以运行Angular 2的单元测试，并查看测试结果。