How to reduce url length in C#

I needed the other day to reduce the length of a URL - so I decided to use a URL reducing service like tinyurl.com And I thought I would share the C# .Net code - nothing new I'm sure and there are plenty of examples out there.

public sealed class TinyUrlReducer : IReduceUrls
{
    private readonly string _tinyUrl;
    private readonly string _proxyUrl;

    public TinyUrlReducer(string tinyUrl) : this(tinyUrl, null)
    {
    }

    public TinyUrlReducer(string tinyUrl, string proxyUrl)
    {
        _tinyUrl = tinyUrl;
        _proxyUrl = proxyUrl;
    }

    public string Reduce(string url)
    {
        if (string.IsNullOrEmpty(url))
            throw new ArgumentException("Can reduce a null or empty url!", "url");

        var reducedUrl = "";
        try
        {
            Trace.WriteLine(string.Format("Reduce: Url - '{0}'.", url));

            var requestUrl = string.Format("{0}?url={1}", _tinyUrl, url);
            var request = (HttpWebRequest)WebRequest.Create(requestUrl);
            request.KeepAlive = false;
            request.UseDefaultCredentials = true;
            request.AllowAutoRedirect = true;
            request.UseDefaultCredentials = true;

            if (!string.IsNullOrEmpty(_proxyUrl))
                request.Proxy = new WebProxy(_proxyUrl, true, null, CredentialCache.DefaultCredentials);

            var response = (HttpWebResponse)request.GetResponse();
            if (response.StatusCode != HttpStatusCode.OK)
                throw new WebException(string.Format("Failed to call url - '{0}'!", requestUrl));

            using (var stream = new StreamReader(response.GetResponseStream()))
            {
                reducedUrl = stream.ReadLine();
            }

            if (string.IsNullOrEmpty(reducedUrl))
                throw new Exception("Reduced url is null or empty!");
        }
        catch (Exception exn)
        {
            Trace.WriteLine(string.Format("Reduce: Failed to reduce url, message - '{0}'.", exn.Message));
            reducedUrl = url;
        }
        finally
        {
            Trace.WriteLine(string.Format("Reduce: Reduced Url - '{0}'.", reducedUrl));
        }

        return reducedUrl;
    }
}

And a couple of tests...

[TestFixture]
public class TinyUrlReducerTests
{
    [Test]
    public void ShouldReduceUrl()
    {
        // Given we have url reducer...
        var reducer = new TinyUrlReducer("http://tinyurl.com/api-create.php", "http://PROXY.MY.COM:8080");

        // When we reduce a url..
        var reducedUrl = reducer.Reduce("http://somereallylongurl/whichhasarelativelylongname/somepage.aspx");

        // Then we expect the reduced url to start with...
        Assert.IsTrue(reducedUrl.ToLower().StartsWith("http://tinyurl.com/"));
    }

    [Test, ExpectedException(typeof(ArgumentException))]
    public void ShouldThrowExceptionIfUrlNull()
    {
        // Given we have url reducer...
        var reducer = new TinyUrlReducer("http://tinyurl.com/api-create.php", "http://PROXY.MY.COM:8080");

        // When we reduce a url..
        var reducedUrl = reducer.Reduce(null);

        // Then we expect the reduced url to start with...
        Assert.IsTrue(reducedUrl.ToLower().StartsWith("http://tinyurl.com/"));
    }

    [Test, ExpectedException(typeof(ArgumentException))]
    public void ShouldThrowExceptionIfUrlEmpty()
    {
        // Given we have url reducer...
        var reducer = new TinyUrlReducer("http://tinyurl.com/api-create.php", "http://PROXY.MY.COM:8080");

        // When we reduce a url..
        var reducedUrl = reducer.Reduce(string.Empty);

        // Then we expect the reduced url to start with...
        Assert.IsTrue(reducedUrl.ToLower().StartsWith("http://tinyurl.com/"));
    }

    [Test]
    public void ShouldReturnOrginalUrlWhenReducerFails()
    {
        // Given we have url reducer...
        var reducer = new TinyUrlReducer("http://tinyurl.com/api-create.php");

        // When we reduce a url and we know it will fail..
        var url = "http://somereallylongurl/whichhasarelativelylongname/somepage.aspx";
        var reducedUrl = reducer.Reduce(url);

        // Then we expect the reduced url to the same as the original url...
        Assert.AreEqual(url, reducedUrl);
    }
}