之前如果对 asp.net WebAPI 进行单元测试（HttpClient 发起请求，并且可调试 WebAPI），一般采用 Owin 的方式，具体参考：《开发笔记：用 Owin Host 实现脱离 IIS 跑 Web API 单元测试》

示例代码：

public class ValuesWebApiTest : IDisposable
{
    PRivate const string HOST_ADDRESS = "http://localhost:8001";
    private IDisposable _webApp;
    private HttpClient _httClient;

    public AdTextUnitWebApiTest()
    {
        _webApp = WebApp.Start<Startup>(HOST_ADDRESS);
        Console.WriteLine("Web API started!");
        _httClient = new HttpClient();
        _httClient.BaseAddress = new Uri(HOST_ADDRESS);
        Console.WriteLine("HttpClient started!");
    }

    [Fact]
    public async Task Get()
    {
        var response = await _httClient.GetAsync("/api/values");
        if (response.StatusCode != HttpStatusCode.OK)
        {
            Console.WriteLine(response.StatusCode);
            Console.WriteLine((await response.Content.ReadAsAsync<HttpError>()).ExceptionMessage);
        }
        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
        var test = await response.Content.ReadAsStringAsync();
        Console.WriteLine(await response.Content.ReadAsStringAsync());
    }

    public void Dispose()
    {
        _httClient.Dispose();
        _webApp.Dispose();
    }
}

本来想在 ASP.NET 5 WebAPI 项目中，也用这一套测试代码，但发现并不适用，因为 ASP.NET WebAPI 2 和 ASP.NET 5 WebAPI 并不是特别一样，比如 Startup.cs 的配置等等，之前使用 WebApp.Start<Startup>(HOST_ADDRESS) 的方式启动 WebAPI 项目，而 ASP.NET 5 WebAPI 变成了这样的：

public static void Main(string[] args) => Webapplication.Run<Startup>(args);

想用 WebApplication.Run 的方式替换掉 WebApp.Start，但发现并不可行，比如 args 的参数问题，自己想的有点简单了，后来 Google 搜索了一些资料，发现 ASP.NET 5 增加了 TestServer，自己找资料配置了很久，看别人的示例代码很简单，但我运行的时候就是各种报错，主要原因是程序包的版本不对，因为我是按照 project.json 的提示安装的，比如 Microsoft.AspNet.TestHost 这个程序包，提示最新版本为 1.0.0-rc2-15960，并且没有 1.0.0-rc1-final 版本，然后我就安装提示安装的 rc2，就报下面的异常：

异常信息：Could not load type 'Microsoft.AspNet.Builder.RequestDelegate' from assembly 'Microsoft.AspNet.Http.Abstractions, Version=1.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'.

根据提示，我以为异常原因是没有加载 Microsoft.AspNet.Http.Abstractions 程序集，然后又添加此程序集，重新运行发现还是报错。。。后面具体的过程就不记录了，反正坑很大，根本原因是 Microsoft.AspNet.TestHost 程序包的版本不对，应该安装 1.0.0-rc1-final 版本，我是后来无意间重启 VS2015 发现的。

下面贴一下 ASP.NET 5 进行单元测试的一些代码。

首先 ASP.NET 5 WebAPI 项目 Startup.cs 配置代码：

using Microsoft.AspNet.Builder;
using Microsoft.AspNet.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

namespace Demo.WebApi
{
    public class Startup
    {
        public Startup(IHostingEnvironment env)
        {
            // Set up configuration sources.
            var builder = new ConfigurationBuilder()
                .AddJsonFile("appsettings.json")
                .AddEnvironmentVariables();
            Configuration = builder.Build();
        }

        public IConfigurationRoot Configuration { get; set; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            // Add framework services.
            services.AddMvc();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddConsole(Configuration.GetSection("Logging"));
            loggerFactory.AddDebug();

            app.UseIISPlatformHandler();

            app.UseStaticFiles();

            app.UseMvc();
        }

        // Entry point for the application.
        public static void Main(string[] args) => WebApplication.Run<Startup>(args);
    }
}

ValuesWebApiTest 测试代码：

using Microsoft.AspNet.Hosting;
using Microsoft.AspNet.TestHost;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

namespace Demo.WebApiTests
{
    public class ValuesWebApiTest
    {
        public TestServer _server;

        public ValuesWebApiTest()
        {
            _server = TestServer.Create(app =>
            {
                var env = app.ApplicationServices.GetRequiredService<IHostingEnvironment>();
                var loggerFactory = app.ApplicationServices.GetRequiredService<ILoggerFactory>();
                new CNBlogs.Ad.WebApi.Startup(env).Configure(app, env, loggerFactory);
            }, services =>
            {
                services.AddMvc();
                services.Configure();
            });
        }
    }

    [Fact]
    public async Task Get()
    {
        var response = await _server.CreateClient().GetAsync("/api/values");
        if (response.StatusCode != HttpStatusCode.OK)
        {
            Console.WriteLine(response.StatusCode);
            Console.WriteLine((await response.Content.ReadAsAsync<HttpError>()).ExceptionMessage);
        }
        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
        var test = await response.Content.ReadAsStringAsync();
        Console.WriteLine(await response.Content.ReadAsStringAsync());
    }
}

project.json 配置代码：

{
  "frameworks": {
    "dnx451": { }
  },
  "dependencies": {
    "Microsoft.AspNet.Mvc.WebApiCompatShim": "6.0.0-rc1-final",
    "Microsoft.Net.Http": "2.2.29",
    "Microsoft.AspNet.TestHost": "1.0.0-rc1-final",
    "xunit": "2.1.0",
    "xunit.runner.dnx": "2.1.0-rc1-build204"
  },
  "commands": {
    "test": "xunit.runner.dnx"
  }
}

运行测试成功，并且可以 Debug 调试，需要注意 using 引用（没用的我都去掉了），还有程序包的版本号。

参考资料：

• Integration testing ASP.NET 5 and ASP.NET MVC 6 applications | StrathWeb. A free flowing web tech monologue.
• Writing integration tests for ASP.NET 5
• Testing asp.net 5 vnext middleware from a TestServer - Stack Overflow