Code to get a mocked HttpContext for unit testing

gistfile1.cs

            private HttpContext GetContext(IEnumerable<KeyValuePair<string,string>> postVariables)
            {
                postVariables = postVariables ?? Enumerable.Empty<KeyValuePair<string, string>>();
                var context = new System.Web.HttpContext(
                    new System.Web.HttpRequest("", "http://tempuri.org", ""),
                    new HttpResponse(new StringWriter()));
                var sessionContainer = new System.Web.SessionState.HttpSessionStateContainer("id", new System.Web.SessionState.SessionStateItemCollection(),
                                        new HttpStaticObjectsCollection(), 10, true,
                                        HttpCookieMode.AutoDetect,
                                        System.Web.SessionState.SessionStateMode.InProc, false);
                context.Items["AspSession"] = typeof(System.Web.SessionState.HttpSessionState).GetConstructor(
                                System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance,
                                null, System.Reflection.CallingConventions.Standard,
                                new[] { typeof(System.Web.SessionState.HttpSessionStateContainer) },
                                null)
                        .Invoke(new object[] { sessionContainer });

                // Make sure forms auth subsystem has initialized
                var existingCookieMode = System.Web.Security.FormsAuthentication.CookieMode;
                // Now set the internal field to use cookies to avoid NRE
                typeof(System.Web.Security.FormsAuthentication).GetField("_CookieMode", System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.NonPublic).SetValue(null, System.Web.HttpCookieMode.UseCookies);

                context.Request.Browser = new HttpBrowserCapabilities();
                context.Request.Browser.Capabilities = new Dictionary<string, string> { { "requiresPostRedirectionHandling", "false" } };
                context.Request.ContentEncoding = System.Text.Encoding.UTF8;
                //context.Request.Browser["requiresPostRedirectionHandling"] = "false";
                var postType = context.Request.Form.GetType();
                postType.GetMethod("MakeReadWrite", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance).Invoke(context.Request.Form, new object[]{}); //hack unto them as they hack unto us.
                foreach (var variable in postVariables)
                    context.Request.Form.Add(variable.Key, variable.Value);
                return context;
            }