Make redirect test case really 'redirect' (#26674)

The test case was redirecting to the same URL this was bringing instability with the handlers (more with the managed). This change should make the test more reliable, as such moving it to inner loop.

Fixes #23769
Since no action is planned for #26434 this also closes #26434

Author: Paulo Janotti

src/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.cs

@@ -568,13 +568,17 @@ public async Task GetAsync_AllowAutoRedirectFalse_RedirectFromHttpToHttp_StatusC
             }
         }
 
-        [ActiveIssue(23769)]
-        [ActiveIssue(22707, TestPlatforms.AnyUnix)]
-        [OuterLoop] // TODO: Issue #11345
         [Theory, MemberData(nameof(RedirectStatusCodesOldMethodsNewMethods))]
         public async Task AllowAutoRedirect_True_ValidateNewMethodUsedOnRedirection(
             int statusCode, string oldMethod, string newMethod)
         {
+            if (!PlatformDetection.IsWindows && !UseManagedHandler && statusCode == 300 && oldMethod == "POST")
+            {
+                // Known behavior: curl does not change method to "GET"
+                // https://github.com/dotnet/corefx/issues/26434
+                newMethod = "POST";
+            }
+
             HttpClientHandler handler = CreateHttpClientHandler();
             using (var client = new HttpClient(handler))
             {
@@ -584,29 +588,34 @@ await LoopbackServer.CreateServerAsync(async (origServer, origUrl) =>
 
                     Task<HttpResponseMessage> getResponseTask = client.SendAsync(request);
 
-                    Task<List<string>> serverTask = LoopbackServer.ReadRequestAndSendResponseAsync(origServer,
-                            $"HTTP/1.1 {statusCode} OK\r\n" +
-                            $"Date: {DateTimeOffset.UtcNow:R}\r\n" +
-                            $"Location: {origUrl}\r\n" +
-                            "\r\n");
-                    await Task.WhenAny(getResponseTask, serverTask);
-                    Assert.False(getResponseTask.IsCompleted, $"{getResponseTask.Status}: {getResponseTask.Exception}");
-                    await serverTask;
-
-                    serverTask = LoopbackServer.ReadRequestAndSendResponseAsync(origServer,
-                            $"HTTP/1.1 200 OK\r\n" +
-                            $"Date: {DateTimeOffset.UtcNow:R}\r\n" +
-                            "\r\n");
-                    await TestHelper.WhenAllCompletedOrAnyFailed(getResponseTask, serverTask);
+                    await LoopbackServer.CreateServerAsync(async (redirServer, redirUrl) =>
+                    {
+                        // Original URL will redirect to a different URL
+                        Task<List<string>> serverTask = LoopbackServer.ReadRequestAndSendResponseAsync(origServer,
+                                $"HTTP/1.1 {statusCode} OK\r\n" +
+                                $"Date: {DateTimeOffset.UtcNow:R}\r\n" +
+                                $"Location: {redirUrl}\r\n" +
+                                "\r\n");
+                        await Task.WhenAny(getResponseTask, serverTask);
+                        Assert.False(getResponseTask.IsCompleted, $"{getResponseTask.Status}: {getResponseTask.Exception}");
+                        await serverTask;
+
+                        // Redirected URL answers with success
+                        serverTask = LoopbackServer.ReadRequestAndSendResponseAsync(redirServer,
+                                $"HTTP/1.1 200 OK\r\n" +
+                                $"Date: {DateTimeOffset.UtcNow:R}\r\n" +
+                                "\r\n");
+                        await TestHelper.WhenAllCompletedOrAnyFailed(getResponseTask, serverTask);
 
-                    List<string> receivedRequest = await serverTask;
-                    string[] statusLineParts = receivedRequest[0].Split(' ');
+                        List<string> receivedRequest = await serverTask;
+                        string[] statusLineParts = receivedRequest[0].Split(' ');
 
-                    using (HttpResponseMessage response = await getResponseTask)
-                    {
-                        Assert.Equal(200, (int)response.StatusCode);
-                        Assert.Equal(newMethod, statusLineParts[0]);
-                    }
+                        using (HttpResponseMessage response = await getResponseTask)
+                        {
+                            Assert.Equal(200, (int)response.StatusCode);
+                            Assert.Equal(newMethod, statusLineParts[0]);
+                        }
+                    });
                 });
             }
         }