Unit test a webrequest that uses a proxy

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hi there,

i'm writing an application that is getting some data from the web over a proxy. as core function i use the simple-http-proxy-class from this site. (can be seen below)

as my app is runnning only somehow and i don't know if everything is going as i want it to, i researched the web and i came accross unit testing. i already implemented many tests, but have absolutly no idea how to test something that would need imput from an external source.

i found some solutions on the web, but there's no solution, that is testing a "proxified" connection.

actually i don't want to test this class, but i want somebody to help me with this, so is understand how it would work.

greetings
delicious_cake

the simple http class:

C#

class simplehttp
{
 public string geturl(string url, string proxyip, int port, string proxylogin, string proxypassword)
 {
  HttpWebResponse resp;
  HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
  req.UserAgent = "Mozilla/5.0";
  req.AllowAutoRedirect = true;
  req.ReadWriteTimeout = 5000;
  req.CookieContainer = new CookieContainer();
  req.Referer = "";
  req.Headers.Set("Accept-Language", "en,en-us");
  StreamReader stream_in;

  WebProxy proxy = new WebProxy(proxyip, port);
  //if proxylogin is an empty string then don't use proxy credentials (open proxy)
  if (proxylogin != "") proxy.Credentials = new NetworkCredential(proxylogin, proxypassword);
  req.Proxy = proxy;

  string response = "";
  try
  {
   resp = (HttpWebResponse)req.GetResponse();
   stream_in = new StreamReader(resp.GetResponseStream());
   response = stream_in.ReadToEnd();
   stream_in.Close();
  }
  catch (Exception ex)
  {
  }
  return response;
 }
}

PS:

i already tried to make a local proxy and a local webserver and perfom something like an integration test.
its working, if the:
1. proxy is correct and url is correct --> behaves as ecpected
2. proxy is correct and url is incorrect --> behaves as expected
3. proxy is incorrect and url is correct --> don't behaves as expected. the url content is returned by the function even if the port thats should be used by the function is no local proxy

i have no idea, why the function returns the url content with this setup.

Posted 21-Dec-11 1:39am

delicious cake

Updated 21-Dec-11 1:49am

v2

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Henning Dieterichs · Answer 1 · 2011-12-21T07:20:00

The proxy typically has a different port than the service you are trying to consume.

Here are some improvements you should consider:
* SimpleHttp is no real "class" in object-orientated manner. You have simply a class that contains a method. Better: Provide an IStringDataProvider Interface which could look like:

C#

public interface IStringDataProvider
{
  string GetContent();
}

Then you are able to get the content from other sources than http - and your testing will be easier as you can replace it with a mock-provider. The url can be passed to the http-provider-instance with dependency injection (see code below).

* GetUrl sounds like "Hey, get me the url!". Better: GetContent or GetContentByUrl
* Dont pass all the proxy-propertys on each request. Better: Set the WebRequest.DefaultWebProxy at application startup. Then you are independent of using a proxy or not and your whole application will use the same proxy.

* Dont swallow exceptions! Either you have a TryGetContent-Method returning whether the operation succeeded or you handle the exception when you want to check whether an error occured - this is typically done in the GUI.

Putting all together:

C#

interface IStringDataProvider
{
    string GetContent();
}

class HttpStringDataProvider : IStringDataProvider
{
    public HttpStringDataProvider(string url) //The url is passed with dependency injection i.e. through parameters on construction
    {
        Url = url;
    }

    public string Url { get; private set; }

    private CookieContainer cookies = new CookieContainer();

    public string GetContent()
    {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);

        request.UserAgent = "Mozilla/5.0";
        request.AllowAutoRedirect = true;
        request.ReadWriteTimeout = 5000;
        request.CookieContainer = cookies;
        request.Referer = "";
        request.Headers.Set("Accept-Language", "en,en-us");

        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        StreamReader streamReader = new StreamReader(response.GetResponseStream());
        return streamReader.ReadToEnd();
    }
}

On startup:

if (proxyType == "http")
{
    WebProxy proxy = new WebProxy(myProxyHost, myProxyPort);
    proxy.Credentials = new NetworkCredential(myProxyUsername, myProxyPassword);
    WebRequest.DefaultWebProxy = proxy; //This proxy will be used by all HttpWebRequests if their Proxy-Property is not set.
}
else if (proxyType == "system")
{
    WebRequest.DefaultWebProxy = WebRequest.GetSystemWebProxy(); //Settings from Internet Explorer (default)
}
else if (proxyType == "no")
{
    WebRequest.DefaultWebProxy = null; //This will speed up the whole a lot, because the default is the proxy used by IE and otherwise the .Net-Framework tries to gather the IE-proxy settings on each request which is very slow
}