Question

I’m trying to use WebRequest.RegisterPrefix to register a decorator IWebRequestCreate implementation with the intention being to add “debug” scenarios (like emulating different connectivity scenarios).

I’m using the Mango beta 2 SDK and the RegisterPrefix method always returns true when used with “http://” as a prefix (or “http” for that matter), but the registered IWebRequestCreate instance is not being used.

I can see from the documentation that it should return false for duplicates, but it doesn’t seem to be functioning as documented.

Is there any other way of achieving what I’m after in a way that is transparent to consumers?

Answer 1

I’m using WebRequest.RegisterPrefix for unit testing, registering an IWebRequestCreate implementation for a prefix of test://, and this does work.

I found that after registering an IWebRequestCreate for http://, calling WebRequest.Create with an http:// uri would return a request created from the registered IWebRequestCreate, but calling WebRequest.CreateHttp would still return an HttpWebRequest.

The following code should verify this, and I’m using the Mango Beta 2 SDK (6-29-11):

public partial class MainPage : PhoneApplicationPage
{
    public class FakeRequest : WebRequest
    {
        private Uri _uri;

        public FakeRequest(Uri uri)
        {
            _uri = uri;
        }

        public override Uri RequestUri { get { return _uri; } }
    }

    public class FakeRequestFactory : IWebRequestCreate
    {
        public WebRequest Create(Uri uri)
        {
            return new FakeRequest(uri);
        }
    }

    // Constructor
    public MainPage()
    {
        InitializeComponent();

        // returns System.Net.Browser.ClientHttpWebRequest
        var request1 = WebRequest.Create("http://www.foo.com");

        // returns System.Net.Browser.ClientHttpWebRequest
        var request2 = WebRequest.CreateHttp("http://www.foo.com"); 

        // returns true
        bool result1 = WebRequest.RegisterPrefix("http://", new FakeRequestFactory());

        // returns FakeRequest
        var request3 = WebRequest.Create("http://www.foo.com");

        // returns System.Net.Browser.ClientHttpWebRequest
        var request4 = WebRequest.CreateHttp("http://www.foo.com");

        // returns false
        bool result2 = WebRequest.RegisterPrefix("http://", new FakeRequestFactory());

        // returns false, as per the note in the documention
        bool result3 = HttpWebRequest.RegisterPrefix("http://", new FakeRequestFactory());
    }
}