可测试的HttpModule和HttpHandler

用新的System.Web.Abstraction名称空间我们能轻易写出可测试的HttpModule和HttpHandler。在这篇post中，
我将向你展示如何写可测试的HttpModule和HttpHandler。

之前发布的System.Web.Abstraction的单元测试这些web的基础构件HttpContext的问题。它是密封的，无法用Rhino或Moq来mock.唯一的选择是为这些不能MOCK的对象创建包装对象，但它又有像HttpRequest, HttpResponse, HttpSessionState, HttpServerUtility等。同时这的确是System.Web.Abstraction所提供的，所有包在外面不可mock的HttpContext对象。但是HttpModule 和HttpHandler紧密依赖于原生HttpContext之上，我希望ASP.NET 4.0将改变，直到我们需要创建一个特别层来实现对它的单元测试。

HttpModule

public abstract class BaseHttpModule : IHttpModule
{
    public void Init(HttpApplication context)
    {
        context.BeginRequest += (sender, e) => OnBeginRequest(new HttpContextWrapper(((HttpApplication) sender).Context));
        context.Error += (sender, e) => OnError(new HttpContextWrapper(((HttpApplication) sender).Context));
        context.EndRequest += (sender, e) => OnEndRequest(new HttpContextWrapper(((HttpApplication) sender).Context));
    }

    public void Dispose()
    {
    }

    public virtual void OnBeginRequest(HttpContextBase context)
    {
    }

    public virtual void OnError(HttpContextBase context)
    {
    }

    public virtual void OnEndRequest(HttpContextBase context)
    {
    }
}

public abstract class BaseHttpModule : IHttpModule
{
    public void Init(HttpApplication context)
    {
        context.BeginRequest += (sender, e) => OnBeginRequest(new HttpContextWrapper(((HttpApplication) sender).Context));
        context.Error += (sender, e) => OnError(new HttpContextWrapper(((HttpApplication) sender).Context));
        context.EndRequest += (sender, e) => OnEndRequest(new HttpContextWrapper(((HttpApplication) sender).Context));
    }

    public void Dispose()
    {
    }

    public virtual void OnBeginRequest(HttpContextBase context)
    {
    }

    public virtual void OnError(HttpContextBase context)
    {
    }

    public virtual void OnEndRequest(HttpContextBase context)
    {
    }
}}

如果你的应用程序需要，它能挂起其它事件。现在让我们创建一个基本的从url访问的HttpModule:

public class RemoveWwwModule : BaseHttpModule
{
    public override void OnBeginRequest(HttpContextBase context)
    {
        const string Prefix = "http://www.";

        string url = context.Request.Url.ToString();

        bool startsWith3W = url.StartsWith(Prefix, StringComparison.OrdinalIgnoreCase);

        if (startsWith3W)
        {
            string newUrl = "http://" + url.Substring(Prefix.Length);

            HttpResponseBase response = context.Response;

            response.StatusCode = (int) HttpStatusCode.MovedPermanently;
            response.Status = "301 Moved Permanently";
            response.RedirectLocation = newUrl;
            response.SuppressContent = true;
            response.End();
        }
    }
}

public class RemoveWwwModule : BaseHttpModule
{
    public override void OnBeginRequest(HttpContextBase context)
    {
        const string Prefix = "http://www.";

        string url = context.Request.Url.ToString();

        bool startsWith3W = url.StartsWith(Prefix, StringComparison.OrdinalIgnoreCase);

        if (startsWith3W)
        {
            string newUrl = "http://" + url.Substring(Prefix.Length);

            HttpResponseBase response = context.Response;

            response.StatusCode = (int) HttpStatusCode.MovedPermanently;
            response.Status = "301 Moved Permanently";
            response.RedirectLocation = newUrl;
            response.SuppressContent = true;
            response.End();
        }
    }
}

Unit Test:

public class RemoveWwwModuleFixture
{
    private readonly Mock<HttpContextBase> _httpContext;
    private readonly Mock<HttpRequestBase> _httpRequest;
    private readonly Mock<HttpResponseBase> _httpResponse;

    public RemoveWwwModuleFixture()
    {
        _httpContext = new Mock<HttpContextBase>();
        _httpRequest = new Mock<HttpRequestBase>();
        _httpResponse = new Mock<HttpResponseBase>();

        _httpContext.SetupGet(context => context.Request).Returns(_httpRequest.Object);
        _httpContext.SetupGet(context => context.Response).Returns(_httpResponse.Object);
    }

    [Fact]
    public void OnBeginRequest_Should_Redirect_When_Requesting_Url_Which_Starts_With_WWW()
    {
        _httpRequest.SetupGet(request => request.Url).Returns(new Uri("http://www.mysite.com/"));

        _httpResponse.SetupSet(response => response.StatusCode = (int) HttpStatusCode.MovedPermanently);
        _httpResponse.SetupSet(response => response.Status = "301 Moved Permanently");
        _httpResponse.SetupSet(response => response.RedirectLocation = "http://mysite.com/");
        _httpResponse.SetupSet(response => response.SuppressContent = true);
        _httpResponse.Setup(response => response.End());

        var module = new RemoveWwwModule();

        module.OnBeginRequest(_httpContext.Object);

        _httpResponse.VerifyAll();
    }
}

public class RemoveWwwModuleFixture
{
    private readonly Mock<HttpContextBase> _httpContext;
    private readonly Mock<HttpRequestBase> _httpRequest;
    private readonly Mock<HttpResponseBase> _httpResponse;

    public RemoveWwwModuleFixture()
    {
        _httpContext = new Mock<HttpContextBase>();
        _httpRequest = new Mock<HttpRequestBase>();
        _httpResponse = new Mock<HttpResponseBase>();

        _httpContext.SetupGet(context => context.Request).Returns(_httpRequest.Object);
        _httpContext.SetupGet(context => context.Response).Returns(_httpResponse.Object);
    }

    [Fact]
    public void OnBeginRequest_Should_Redirect_When_Requesting_Url_Which_Starts_With_WWW()
    {
        _httpRequest.SetupGet(request => request.Url).Returns(new Uri("http://www.mysite.com/"));

        _httpResponse.SetupSet(response => response.StatusCode = (int) HttpStatusCode.MovedPermanently);
        _httpResponse.SetupSet(response => response.Status = "301 Moved Permanently");
        _httpResponse.SetupSet(response => response.RedirectLocation = "http://mysite.com/");
        _httpResponse.SetupSet(response => response.SuppressContent = true);
        _httpResponse.Setup(response => response.End());

        var module = new RemoveWwwModule();

        module.OnBeginRequest(_httpContext.Object);

        _httpResponse.VerifyAll();
    }
}}

HttpHandler

public abstract class BaseHttpHandler : IHttpHandler
{
    public virtual bool IsReusable
    {
        get
        {
            return false;
        }
    }

    public void ProcessRequest(HttpContext context)
    {
        ProcessRequest(new HttpContextWrapper(context));
    }

    public abstract void ProcessRequest(HttpContextBase context);
}

现在让我们创建结合些Javascript文件的HttpHandler,我将在Post中跳过如果是不相关的部分。

public class JavaScriptHandler : BaseHttpHandler
{
    public override void ProcessRequest(HttpContextBase context)
    {
        string content = GetContent();
        HttpResponseBase response = context.Response;

        response.ContentType = "application/x-javascript";
        response.Write(content);
    }

    private string GetContent()
    {
        return "YOUR JAVA SCRIPT FILES CONTENT";
    }
}

public class JavaScriptHandler : BaseHttpHandler
{
    public override void ProcessRequest(HttpContextBase context)
    {
        string content = GetContent();
        HttpResponseBase response = context.Response;

        response.ContentType = "application/x-javascript";
        response.Write(content);
    }

    private string GetContent()
    {
        return "YOUR JAVA SCRIPT FILES CONTENT";
    }
}

Unit Test:

public class JavaScriptHandlerFixture : IDisposable
{
    private readonly Mock<HttpContextBase> _httpContext;
    private readonly Mock<HttpResponseBase> _httpResponse;

    private readonly JavaScriptHandler _handler;

    public JavaScriptHandlerFixture()
    {
        _httpContext = new Mock<HttpContextBase>();
        _httpResponse = new Mock<HttpResponseBase>();

        _httpContext.SetupGet(context => context.Response).Returns(_httpResponse.Object);

        _handler = new JavaScriptHandler();
    }

    public void Dispose()
    {
        _httpResponse.VerifyAll();
    }

    [Fact]
    public void ProcessRequest_Should_Set_Correct_ContentType()
    {
        _httpResponse.SetupSet(response => response.ContentType = "application/x-javascript");

        _handler.ProcessRequest(_httpContext.Object);
    }

    [Fact]
    public void ProcessRequest_Should_Write_Content()
    {
        _httpResponse.Setup(response => response.Write(It.IsAny<string>()));

        _handler.ProcessRequest(_httpContext.Object);
    }
}

public class JavaScriptHandlerFixture : IDisposable
{
    private readonly Mock<HttpContextBase> _httpContext;
    private readonly Mock<HttpResponseBase> _httpResponse;

    private readonly JavaScriptHandler _handler;

    public JavaScriptHandlerFixture()
    {
        _httpContext = new Mock<HttpContextBase>();
        _httpResponse = new Mock<HttpResponseBase>();

        _httpContext.SetupGet(context => context.Response).Returns(_httpResponse.Object);

        _handler = new JavaScriptHandler();
    }

    public void Dispose()
    {
        _httpResponse.VerifyAll();
    }

    [Fact]
    public void ProcessRequest_Should_Set_Correct_ContentType()
    {
        _httpResponse.SetupSet(response => response.ContentType = "application/x-javascript");

        _handler.ProcessRequest(_httpContext.Object);
    }

    [Fact]
    public void ProcessRequest_Should_Write_Content()
    {
        _httpResponse.Setup(response => response.Write(It.IsAny<string>()));

        _handler.ProcessRequest(_httpContext.Object);
    }
}}

如果你要看更多的可单元测试HttpModule and HttpHandler，到KiGG源代中查看吧。

翻译:Petter Liu   http://wintersun.cnblogs.com   原文：Source