集成测试 - 此操作需要IIS集成管道模式

我正在使用VS 2015与.Net 4.6.1。我正在尝试为代码编写集成测试，但它给了我上面的错误。我无法摆弄我的头。这种方法是在Global.asax中集成测试 - 此操作需要IIS集成管道模式

public void Application_EndRequest(object sender, EventArgs e) 
     { 
      AddCorsResponseHeadersForUnauthorizedRequests(Response, Request); 
     } 

     public static void AddCorsResponseHeadersForUnauthorizedRequests(HttpResponse response, HttpRequest request) 
     { 
      var origin = request.Params[AppConstant.RequestHttpOrigin]; 
      if (response.StatusCode == (int) HttpStatusCode.Unauthorized && 
       string.IsNullOrEmpty(response.Headers[AppConstant.AccessControlAllowOrigin]) && 
       !string.IsNullOrEmpty(origin)) 
      { 
       response.AddHeader(AppConstant.AccessControlAllowOrigin, WebApiConfig.GetCorsAllowedOrigin()); 
       response.AddHeader(AppConstant.AccessControlAllowCredentials, "true"); 
      } 
     }

IntegrationTest.cs

[TestFixture] 
    public class AuthenticationResponseHeadersTests 
    { 
     private WebApiApplication systemUnderTest; 
     private HttpRequest httpRequest; 
     private HttpResponse httpResponse; 

     [SetUp] 
     public void Setup() 
     { 
      systemUnderTest = new WebApiApplication(); 
      httpRequest = new HttpRequest(string.Empty, "http://localhost:5001/", string.Empty); 
      httpResponse = new HttpResponse(TextWriter.Null); 
      httpResponse.AddHeader("Connection", "keep-alive"); 
     } 

     [Test] 
     public void ShouldAddCorsResponseHeaders() 
     { 
      httpResponse.StatusCode = (int)HttpStatusCode.Unauthorized; 
      WebApiApplication.AddCorsResponseHeadersForUnauthorizedRequests(httpResponse, httpRequest); 

      Assert.AreEqual("http://localhost:5001", httpResponse.Headers[AppConstant.AccessControlAllowOrigin]); 
      Assert.AreEqual("true", httpResponse.Headers[AppConstant.AccessControlAllowCredentials]); 
     } 
    }

我得到的错误是，如果它正试图获得对Response.Headers特定的标头的条件和错误是，任何想法？为什么它需要IIS进行测试？