/// <summary>
/// Replaces the default <see cref="IWebRequestCreate"/> for "http://" and
/// "https:// urls with a custom <see cref="IWebRequestCreate"/>, such as
/// <see cref="HttpWebRequestWrapperInterceptorCreator"/> or <see cref="HttpWebRequestWrapperRecorderCreator"/>.
/// This will also hook into new <see cref="WebClient"/>s and <see cref="HttpClient"/>s!
/// <para />
/// After creating a <see cref="HttpWebRequestWrapperSession"/>, any code that uses
/// <see cref="WebRequest.Create(System.Uri)"/>, new <see cref="WebClient"/>() or
/// new <see cref="HttpClient"/>() will receive a custom <see cref="HttpWebRequest"/>
/// built by the passed <see cref="IWebRequestCreate"/>.
/// <para />
/// This works by both hijacking <see cref="M:WebRequest.PrefixList"/>
/// and using <see cref="TaskSchedulerProxy"/> and
/// <see cref="HttpClientHandlerStartRequestTaskVisitor"/> to intercept
/// <see cref="System.Net.Http.HttpClient"/> before it begins processing a
/// <see cref="HttpWebRequest"/> / <see cref="HttpRequestMessage"/>
/// <para />
/// NOTE: This technique is only able to support <see cref="System.Net.Http.HttpClient"/>
/// that are using a <see cref="HttpMessageHandler"/> that derives from
/// <see cref="HttpClientHandler"/>. If you are using a purely custom
/// <see cref="HttpMessageHandler"/>, this class will not intercept
/// http requests, you'd need to change how your <see cref="System.Net.Http.HttpClient"/>s
/// are built to fallback to using the default <see cref="HttpClientHandler"/> for
/// test runs.
/// <para />
/// Calling <see cref="Dispose"/> will reset reset the <see cref="M:WebRequest.PrefixList"/>
/// and the <see cref="TaskScheduler.Default"/>; restoring default behavior.
/// <para />
/// See <see cref="HttpWebRequestWrapperSession"/> for more information on
/// how the <see cref="IWebRequestCreate"/> process is intercepted.
/// <para />
/// NOTE: This class does not support concurrency. It relies on manipulating a static field
/// (<see cref="TaskScheduler.Default"/> and <see cref="M:WebRequest.PrefixList"/>).
/// You can only create one Session at a time for a given
/// App Domain. However, you can run concurrent code within the Session.
/// </summary>
public HttpWebRequestWrapperSession(IWebRequestCreate httpRequestCreator)
{
_originalWebRequestPrefixList = WebRequestReflectionExtensions.GetWebRequestPrefixList();
WebRequest.RegisterPrefix("http://", httpRequestCreator);
WebRequest.RegisterPrefix("https://", httpRequestCreator);
_defaultTaskScheduler = TaskScheduler.Current;
// replace the default TaskScheduler.Default with a custom
// proxy that's wired up with the HttpClientHandlerStartRequestTaskVisitor
var httpClientInterceptorTaskScheduler =
new TaskSchedulerProxy(
new IVisitTaskOnSchedulerQueue[]
{
new HttpClientHandlerStartRequestTaskVisitor.DotNet45AndEarlierStrategy(),
new HttpClientHandlerStartRequestTaskVisitor.DotNet47Strategy()
},
TaskScheduler.Current);
httpClientInterceptorTaskScheduler.SetAsDefaultTaskScheduler();
}
/// <summary>
/// Restores the original <see cref="TaskScheduler.Current"/>
/// as well as the work done in <see cref="HttpWebRequestWrapperSession.Dispose"/>
/// </summary>
public virtual void Dispose()
{
WebRequestReflectionExtensions.SetWebRequestPrefixList(_originalWebRequestPrefixList);
_defaultTaskScheduler.SetAsDefaultTaskScheduler();
}
