[wasm][testing] hosting echo server in xharness process (#52923)

- move tests to inner loop
- include echo middleware in xharness server
- improve doc
- more granular ActiveIssue https://github.com/dotnet/runtime/issues/53592 for lack of TRACE
- more granular ActiveIssue https://github.com/dotnet/runtime/issues/53591 for content on GET/HEAD
- more granular ActiveIssue https://github.com/dotnet/runtime/issues/53874 for HttpRequestMessage.Headers.Host
- more granular ActiveIssue https://github.com/dotnet/runtime/issues/53872 for NPE on System.Net.Http.BrowserHttpHandler
- more granular ActiveIssue https://github.com/dotnet/runtime/issues/53876
- include middleware in Helix correlation payload

docs/workflow/testing/libraries/testing-wasm.md

@@ -100,11 +100,11 @@ The following shows how to run tests for a specific library
 
 - `$(WasmXHarnessArgs)` - xharness command arguments
 
-    Example: `WasmXHarnessArgs="--xyz"` -> becomes `dotnet xharness wasm test --xyz`
+    Example: `WasmXHarnessArgs="--set-web-server-http-env=DOTNET_TEST_WEBSOCKETHOST"` -> becomes `dotnet xharness wasm test --set-web-server-http-env=DOTNET_TEST_WEBSOCKETHOST`
 
-- `$(WasmXHarnessMonoArgs)` - arguments to mono
+- `$(WasmXHarnessMonoArgs)` - arguments and variables for mono
 
-    Example: `WasmXHarnessMonoArgs="--runtime-arg=--trace=E"`
+    Example: `WasmXHarnessMonoArgs="--runtime-arg=--trace=E --setenv=MONO_LOG_LEVEL=debug"`
 
 - `$(WasmTestAppArgs)` - arguments for the test app itself
 

src/libraries/Common/tests/System/Net/Configuration.Http.cs

@@ -12,11 +12,12 @@ public static partial class Http
         {
             private static readonly string DefaultHttp2AzureServer = "corefx-net-http2.azurewebsites.net";
 
+            // for the local server hosted in XHarness we are passing also port as part of the environment variables, because it's bound to random port number
             public static string Host => GetValue("DOTNET_TEST_HTTPHOST", DefaultAzureServer);
-
             public static string SecureHost => GetValue("DOTNET_TEST_SECUREHTTPHOST", DefaultAzureServer);
-
             public static string Http2Host => GetValue("DOTNET_TEST_HTTP2HOST", DefaultHttp2AzureServer);
+            public static int Port = GetPortValue("DOTNET_TEST_HTTPHOST", 80);
+            public static int SecurePort = GetPortValue("DOTNET_TEST_SECUREHTTPHOST", 443);
 
             // This server doesn't use HTTP/2 server push (push promise) feature. Some HttpClient implementations
             // don't support servers that use push right now.

src/libraries/Common/tests/System/Net/Configuration.cs

@@ -21,6 +21,25 @@ private static string GetValue(string envName, string defaultValue=null)
             return Environment.ExpandEnvironmentVariables(envValue);
         }
 
+        private static int GetPortValue(string envName, int defaultValue)
+        {
+            string envValue = Environment.GetEnvironmentVariable(envName);
+
+            if (string.IsNullOrWhiteSpace(envValue))
+            {
+                return defaultValue;
+            }
+            envValue = Environment.ExpandEnvironmentVariables(envValue);
+
+            var split = envValue.Split(':');
+            if (split.Length<2)
+            {
+                return defaultValue;
+            }
+            
+            return int.Parse(split[1]);
+        }
+
         private static Uri GetUriValue(string envName, Uri defaultValue=null)
         {
             string envValue = GetValue(envName, null);

src/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.RemoteServer.cs

@@ -77,9 +77,9 @@ public async Task UseDefaultCredentials_SetToFalseAndServerNeedsAuth_StatusCodeU
             }
         }
 
-        [OuterLoop("Uses external servers")]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task SendAsync_SimpleGet_Success(Configuration.Http.RemoteServer remoteServer)
         {
             using (HttpClient client = CreateHttpClientForRemoteServer(remoteServer))
@@ -95,9 +95,8 @@ public async Task SendAsync_SimpleGet_Success(Configuration.Http.RemoteServer re
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
         public async Task SendAsync_MultipleRequestsReusingSameClient_Success(Configuration.Http.RemoteServer remoteServer)
         {
             using (HttpClient client = CreateHttpClientForRemoteServer(remoteServer))
@@ -112,9 +111,9 @@ public async Task SendAsync_MultipleRequestsReusingSameClient_Success(Configurat
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task GetAsync_ResponseContentAfterClientAndHandlerDispose_Success(Configuration.Http.RemoteServer remoteServer)
         {
             using (HttpClient client = CreateHttpClientForRemoteServer(remoteServer))
@@ -162,9 +161,8 @@ public async Task GetAsync_ServerNeedsAuthAndSetCredential_StatusCodeOK(Configur
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
         public async Task GetAsync_ServerNeedsAuthAndNoCredential_StatusCodeUnauthorized(Configuration.Http.RemoteServer remoteServer)
         {
             using (HttpClient client = CreateHttpClientForRemoteServer(remoteServer))
@@ -177,10 +175,10 @@ public async Task GetAsync_ServerNeedsAuthAndNoCredential_StatusCodeUnauthorized
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory]
         [MemberData(nameof(RemoteServersAndHeaderEchoUrisMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/53872", TestPlatforms.Browser)]
         public async Task GetAsync_RequestHeadersAddCustomHeaders_HeaderAndEmptyValueSent(Configuration.Http.RemoteServer remoteServer, Uri uri)
         {
             if (IsWinHttpHandler && !PlatformDetection.IsWindows10Version1709OrGreater)
@@ -204,9 +202,8 @@ public async Task GetAsync_RequestHeadersAddCustomHeaders_HeaderAndEmptyValueSen
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersHeaderValuesAndUris))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
         public async Task GetAsync_RequestHeadersAddCustomHeaders_HeaderAndValueSent(Configuration.Http.RemoteServer remoteServer, string name, string value, Uri uri)
         {
             using (HttpClient client = CreateHttpClientForRemoteServer(remoteServer))
@@ -223,9 +220,8 @@ public async Task GetAsync_RequestHeadersAddCustomHeaders_HeaderAndValueSent(Con
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersAndHeaderEchoUrisMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
         public async Task GetAsync_LargeRequestHeader_HeadersAndValuesSent(Configuration.Http.RemoteServer remoteServer, Uri uri)
         {
             // Unfortunately, our remote servers seem to have pretty strict limits (around 16K?)
@@ -291,9 +287,9 @@ public static IEnumerable<(Configuration.Http.RemoteServer remoteServer, Uri uri
 
         public static IEnumerable<object[]> RemoteServersAndHeaderEchoUrisMemberData() => RemoteServersAndHeaderEchoUris().Select(x => new object[] { x.remoteServer, x.uri });
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task GetAsync_ResponseHeadersRead_ReadFromEachIterativelyDoesntDeadlock(Configuration.Http.RemoteServer remoteServer)
         {
             using (HttpClient client = CreateHttpClientForRemoteServer(remoteServer))
@@ -317,9 +313,9 @@ public async Task GetAsync_ResponseHeadersRead_ReadFromEachIterativelyDoesntDead
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task SendAsync_HttpRequestMsgResponseHeadersRead_StatusCodeOK(Configuration.Http.RemoteServer remoteServer)
         {
             // Sync API supported only up to HTTP/1.1
@@ -344,7 +340,7 @@ public async Task SendAsync_HttpRequestMsgResponseHeadersRead_StatusCodeOK(Confi
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostAsync_CallMethodTwice_StringContent(Configuration.Http.RemoteServer remoteServer)
@@ -370,7 +366,7 @@ public async Task PostAsync_CallMethodTwice_StringContent(Configuration.Http.Rem
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostAsync_CallMethod_UnicodeStringContent(Configuration.Http.RemoteServer remoteServer)
@@ -388,7 +384,7 @@ public async Task PostAsync_CallMethod_UnicodeStringContent(Configuration.Http.R
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(VerifyUploadServersStreamsAndExpectedData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)] 
         public async Task PostAsync_CallMethod_StreamContent(Configuration.Http.RemoteServer remoteServer, HttpContent content, byte[] expectedData)
@@ -528,9 +524,9 @@ public static IEnumerable<object[]> VerifyUploadServersStreamsAndExpectedData
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostAsync_CallMethod_NullContent(Configuration.Http.RemoteServer remoteServer)
         {
             using (HttpClient client = CreateHttpClientForRemoteServer(remoteServer))
@@ -550,9 +546,9 @@ public async Task PostAsync_CallMethod_NullContent(Configuration.Http.RemoteServ
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostAsync_CallMethod_EmptyContent(Configuration.Http.RemoteServer remoteServer)
         {
             using (HttpClient client = CreateHttpClientForRemoteServer(remoteServer))
@@ -581,10 +577,10 @@ public static IEnumerable<object[]> ExpectContinueVersion()
                 select new object[] {expect, version};
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory]
         [MemberData(nameof(ExpectContinueVersion))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/53876", TestPlatforms.Browser)]
         public async Task PostAsync_ExpectContinue_Success(bool? expectContinue, Version version)
         {
             // Sync API supported only up to HTTP/1.1
@@ -622,9 +618,8 @@ public async Task PostAsync_ExpectContinue_Success(bool? expectContinue, Version
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
         public async Task PostAsync_Redirect_ResultingGetFormattedCorrectly(Configuration.Http.RemoteServer remoteServer)
         {
             const string ContentString = "This is the content string.";
@@ -644,7 +639,7 @@ public async Task PostAsync_Redirect_ResultingGetFormattedCorrectly(Configuratio
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostAsync_RedirectWith307_LargePayload(Configuration.Http.RemoteServer remoteServer)
@@ -660,7 +655,7 @@ public async Task PostAsync_RedirectWith307_LargePayload(Configuration.Http.Remo
             await PostAsync_Redirect_LargePayload_Helper(remoteServer, 307, true);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostAsync_RedirectWith302_LargePayload(Configuration.Http.RemoteServer remoteServer)
@@ -716,9 +711,9 @@ private async Task PostAsync_Redirect_LargePayload_Helper(Configuration.Http.Rem
         }
 
 #if !NETFRAMEWORK
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostAsync_ReuseRequestContent_Success(Configuration.Http.RemoteServer remoteServer)
         {
             const string ContentString = "This is the content string.";
@@ -737,14 +732,17 @@ public async Task PostAsync_ReuseRequestContent_Success(Configuration.Http.Remot
         }
 #endif
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(HttpMethods))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53592", TestPlatforms.Browser)]
         public async Task SendAsync_SendRequestUsingMethodToEchoServerWithNoContent_MethodCorrectlySent(
             string method,
             Uri serverUri)
         {
+            if (method == "TRACE" && PlatformDetection.IsBrowser)
+            {
+                // [ActiveIssue("https://github.com/dotnet/runtime/issues/53592", TestPlatforms.Browser)]
+                return;
+            }
             using (HttpClient client = CreateHttpClient())
             {
                 var request = new HttpRequestMessage(
@@ -759,9 +757,10 @@ public async Task PostAsync_ReuseRequestContent_Success(Configuration.Http.Remot
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(HttpMethodsThatAllowContent))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/53591", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task SendAsync_SendRequestUsingMethodToEchoServerWithContent_Success(
             string method,
             Uri serverUri)
@@ -789,14 +788,23 @@ public async Task PostAsync_ReuseRequestContent_Success(Configuration.Http.Remot
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(HttpMethodsThatDontAllowContent))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53591", TestPlatforms.Browser)]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53592", TestPlatforms.Browser)]
         public async Task SendAsync_SendRequestUsingNoBodyMethodToEchoServerWithContent_NoBodySent(
             string method,
             Uri serverUri)
         {
+            if (method == "TRACE" && PlatformDetection.IsBrowser)
+            {
+                // [ActiveIssue("https://github.com/dotnet/runtime/issues/53592", TestPlatforms.Browser)]
+                return;
+            }
+            if (method == "HEAD" && PlatformDetection.IsBrowser)
+            {
+                // [ActiveIssue("https://github.com/dotnet/runtime/issues/53591", TestPlatforms.Browser)]
+                return;
+            }
+
             using (HttpClient client = CreateHttpClient())
             {
                 var request = new HttpRequestMessage(
@@ -836,9 +844,8 @@ public static IEnumerable<object[]> SendAsync_SendSameRequestMultipleTimesDirect
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(SendAsync_SendSameRequestMultipleTimesDirectlyOnHandler_Success_MemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
         public async Task SendAsync_SendSameRequestMultipleTimesDirectlyOnHandler_Success(Configuration.Http.RemoteServer remoteServer, string stringContent, int startingPosition)
         {
             using (var handler = new HttpMessageInvoker(CreateHttpClientHandler()))
@@ -869,10 +876,9 @@ public async Task SendAsync_SendSameRequestMultipleTimesDirectlyOnHandler_Succes
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory]
         [MemberData(nameof(Http2Servers))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
         public async Task SendAsync_RequestVersion20_ResponseVersion20IfHttp2Supported(Uri server)
         {
             // Sync API supported only up to HTTP/1.1

src/libraries/Common/tests/System/Net/Http/PostScenarioTest.cs

@@ -28,9 +28,9 @@ public abstract class PostScenarioTest : HttpClientHandlerTestBase
         public PostScenarioTest(ITestOutputHelper output) : base(output) { }
 
 #if !NETFRAMEWORK
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostRewindableStreamContentMultipleTimes_StreamContentFullySent(Configuration.Http.RemoteServer remoteServer)
         {
             const string requestBody = "ABC";
@@ -53,17 +53,17 @@ public async Task PostRewindableStreamContentMultipleTimes_StreamContentFullySen
         }
 #endif
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [MemberData(nameof(RemoteServersMemberData))]
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsBrowserDomSupportedOrNotBrowser))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostNoContentUsingContentLengthSemantics_Success(Configuration.Http.RemoteServer remoteServer)
         {
             await PostHelper(remoteServer, string.Empty, null,
                 useContentLengthUpload: true, useChunkedEncodingUpload: false);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostEmptyContentUsingContentLengthSemantics_Success(Configuration.Http.RemoteServer remoteServer)
@@ -72,7 +72,7 @@ public async Task PostEmptyContentUsingContentLengthSemantics_Success(Configurat
                 useContentLengthUpload: true, useChunkedEncodingUpload: false);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostEmptyContentUsingChunkedEncoding_Success(Configuration.Http.RemoteServer remoteServer)
@@ -81,7 +81,7 @@ public async Task PostEmptyContentUsingChunkedEncoding_Success(Configuration.Htt
                 useContentLengthUpload: false, useChunkedEncodingUpload: true);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostEmptyContentUsingConflictingSemantics_Success(Configuration.Http.RemoteServer remoteServer)
@@ -90,7 +90,7 @@ public async Task PostEmptyContentUsingConflictingSemantics_Success(Configuratio
                 useContentLengthUpload: true, useChunkedEncodingUpload: true);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostUsingContentLengthSemantics_Success(Configuration.Http.RemoteServer remoteServer)
@@ -99,7 +99,7 @@ public async Task PostUsingContentLengthSemantics_Success(Configuration.Http.Rem
                 useContentLengthUpload: true, useChunkedEncodingUpload: false);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostUsingChunkedEncoding_Success(Configuration.Http.RemoteServer remoteServer)
@@ -108,7 +108,7 @@ public async Task PostUsingChunkedEncoding_Success(Configuration.Http.RemoteServ
                 useContentLengthUpload: false, useChunkedEncodingUpload: true);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostSyncBlockingContentUsingChunkedEncoding_Success(Configuration.Http.RemoteServer remoteServer)
@@ -117,7 +117,7 @@ public async Task PostSyncBlockingContentUsingChunkedEncoding_Success(Configurat
                 useContentLengthUpload: false, useChunkedEncodingUpload: true);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostRepeatedFlushContentUsingChunkedEncoding_Success(Configuration.Http.RemoteServer remoteServer)
@@ -126,7 +126,7 @@ public async Task PostRepeatedFlushContentUsingChunkedEncoding_Success(Configura
                 useContentLengthUpload: false, useChunkedEncodingUpload: true);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostUsingUsingConflictingSemantics_UsesChunkedSemantics(Configuration.Http.RemoteServer remoteServer)
@@ -135,7 +135,7 @@ public async Task PostUsingUsingConflictingSemantics_UsesChunkedSemantics(Config
                 useContentLengthUpload: true, useChunkedEncodingUpload: true);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostUsingNoSpecifiedSemantics_UsesChunkedSemantics(Configuration.Http.RemoteServer remoteServer)
@@ -154,7 +154,7 @@ public static IEnumerable<object[]> RemoteServersAndLargeContentSizes()
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory]
         [MemberData(nameof(RemoteServersAndLargeContentSizes))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
@@ -223,10 +223,10 @@ public async Task PostNonRewindableContentUsingAuth_PreAuthenticate_Success(Conf
             await PostUsingAuthHelper(remoteServer, ExpectedContent, content, credential, preAuthenticate: true);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [MemberData(nameof(RemoteServersMemberData))]
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsBrowserDomSupportedOrNotBrowser))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task PostAsync_EmptyContent_ContentTypeHeaderNotSent(Configuration.Http.RemoteServer remoteServer)
         {
             using (HttpClient client = CreateHttpClientForRemoteServer(remoteServer))

src/libraries/Common/tests/System/Net/Http/ResponseStreamTest.cs

@@ -30,9 +30,9 @@ public static IEnumerable<object[]> RemoteServersAndReadModes()
             }
 
         }
-        [OuterLoop("Uses external servers")]
+
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersAndReadModes))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
         public async Task GetStreamAsync_ReadToEnd_Success(Configuration.Http.RemoteServer remoteServer, int readMode)
         {
             using (HttpClient client = CreateHttpClientForRemoteServer(remoteServer))
@@ -126,9 +126,9 @@ public async Task GetStreamAsync_ReadToEnd_Success(Configuration.Http.RemoteServ
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task GetAsync_UseResponseHeadersReadAndCallLoadIntoBuffer_Success(Configuration.Http.RemoteServer remoteServer)
         {
             using (HttpClient client = CreateHttpClientForRemoteServer(remoteServer))
@@ -146,9 +146,9 @@ public async Task GetAsync_UseResponseHeadersReadAndCallLoadIntoBuffer_Success(C
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task GetAsync_UseResponseHeadersReadAndCopyToMemoryStream_Success(Configuration.Http.RemoteServer remoteServer)
         {
             using (HttpClient client = CreateHttpClientForRemoteServer(remoteServer))
@@ -171,9 +171,8 @@ public async Task GetAsync_UseResponseHeadersReadAndCopyToMemoryStream_Success(C
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
         public async Task GetStreamAsync_ReadZeroBytes_Success(Configuration.Http.RemoteServer remoteServer)
         {
             using (HttpClient client = CreateHttpClientForRemoteServer(remoteServer))
@@ -187,9 +186,8 @@ public async Task GetStreamAsync_ReadZeroBytes_Success(Configuration.Http.Remote
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory, MemberData(nameof(RemoteServersMemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
         public async Task ReadAsStreamAsync_Cancel_TaskIsCanceled(Configuration.Http.RemoteServer remoteServer)
         {
             var cts = new CancellationTokenSource();

src/libraries/Common/tests/System/Net/Prerequisites/LocalEchoServer.props

+<Project>
+  <PropertyGroup Condition="'$(TargetOS)' == 'Browser'">
+    <Scenario>WasmTestOnBrowser</Scenario>
+    <TestArchiveTestsRoot>$(TestArchiveRoot)browseronly/</TestArchiveTestsRoot>
+    <TestArchiveTestsDir>$(TestArchiveTestsRoot)$(OSPlatformConfig)/</TestArchiveTestsDir>
+
+    <!-- handle different path to middleware in Helix -->
+    <_TestEchoMiddleware Condition="'$(ContinuousIntegrationBuild)' == 'true' and '$(OS)' == 'Windows_NT'">%HELIX_CORRELATION_PAYLOAD%/xharness/TestEchoMiddleware</_TestEchoMiddleware>
+    <_TestEchoMiddleware Condition="'$(ContinuousIntegrationBuild)' == 'true' and '$(OS)' != 'Windows_NT'">$HELIX_CORRELATION_PAYLOAD/xharness/TestEchoMiddleware</_TestEchoMiddleware>
+    <_TestEchoMiddleware Condition="'$(ContinuousIntegrationBuild)' != 'true'">$(ArtifactsDir)bin/NetCoreServer/$(NetCoreAppCurrent)-$(Configuration)</_TestEchoMiddleware>
+
+    <WasmXHarnessArgs>$(WasmXHarnessArgs) --web-server-use-cors --web-server-use-https</WasmXHarnessArgs>
+    <WasmXHarnessArgs>$(WasmXHarnessArgs) --set-web-server-http-env=DOTNET_TEST_WEBSOCKETHOST,DOTNET_TEST_HTTPHOST</WasmXHarnessArgs>
+    <WasmXHarnessArgs>$(WasmXHarnessArgs) --set-web-server-https-env=DOTNET_TEST_SECUREWEBSOCKETHOST,DOTNET_TEST_SECUREHTTPHOST,DOTNET_TEST_HTTP2HOST</WasmXHarnessArgs>
+    <WasmXHarnessArgs>$(WasmXHarnessArgs) --web-server-middleware=$(_TestEchoMiddleware)/NetCoreServer.dll,GenericHandler</WasmXHarnessArgs>
+  </PropertyGroup>
+</Project>

src/libraries/Common/tests/System/Net/Prerequisites/NetCoreServer/GenericHandler.cs

@@ -13,7 +13,7 @@ public class GenericHandler
         // Must have constructor with this signature, otherwise exception at run time.
         public GenericHandler(RequestDelegate next)
         {
-            // This is an HTTP Handler, so no need to store next.
+            // This catch all HTTP Handler, so no need to store next.
         }
 
         public async Task Invoke(HttpContext context)

src/libraries/Common/tests/System/Net/Prerequisites/NetCoreServer/NetCoreServer.csproj

 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>$(AspNetCoreAppCurrent)</TargetFramework>
     <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
     <OutputType>Exe</OutputType>
     <EnableDefaultCompileItems>false</EnableDefaultCompileItems>

src/libraries/Common/tests/System/Net/Prerequisites/NetCoreServer/Startup.cs

@@ -11,11 +11,20 @@ public class Startup
     {
         public void ConfigureServices(IServiceCollection services)
         {
+            services.AddCors(o => o.AddPolicy("AnyCors", builder =>
+            {
+                builder.AllowAnyOrigin()
+                    .AllowAnyMethod()
+                    .AllowAnyHeader()
+                    .WithExposedHeaders("*")
+                    ;
+            }));
         }
 
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
         public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
         {
+            app.UseCors("AnyCors");
             app.UseWebSockets();
             app.UseGenericHandler();
         }

src/libraries/Common/tests/TestUtilities/System/PlatformDetection.cs

@@ -9,6 +9,7 @@
 using System.Runtime.InteropServices;
 using System.Runtime.CompilerServices;
 using Microsoft.Win32;
+using Xunit;
 
 namespace System
 {
@@ -59,6 +60,8 @@ public static partial class PlatformDetection
         public static bool IsBrowserDomSupported => GetIsBrowserDomSupported();
         public static bool IsBrowserDomSupportedOrNotBrowser => IsNotBrowser || GetIsBrowserDomSupported();
         public static bool IsNotBrowserDomSupported => !IsBrowserDomSupported;
+        public static bool LocalEchoServerIsNotAvailable => !LocalEchoServerIsAvailable;
+        public static bool LocalEchoServerIsAvailable => IsBrowser;
 
         public static bool IsUsingLimitedCultures => !IsNotMobile;
         public static bool IsNotUsingLimitedCultures => IsNotMobile;

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

@@ -343,11 +343,11 @@ public async Task SendAsync_RequestHeaderInResponse_Success(string name, string
             });
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Theory]
         [InlineData(false)]
         [InlineData(true)]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/37669", TestPlatforms.Browser)]
         public async Task SendAsync_GetWithValidHostHeader_Success(bool withPort)
         {
             if (UseVersion == HttpVersion.Version30)
@@ -355,9 +355,14 @@ public async Task SendAsync_GetWithValidHostHeader_Success(bool withPort)
                 // External servers do not support HTTP3 currently.
                 return;
             }
+            if (PlatformDetection.LocalEchoServerIsAvailable && !withPort)
+            {
+                // we always have custom port with the local echo server, so we couldn't test without it
+                return;
+            }
 
             var m = new HttpRequestMessage(HttpMethod.Get, Configuration.Http.SecureRemoteEchoServer) { Version = UseVersion };
-            m.Headers.Host = withPort ? Configuration.Http.SecureHost + ":443" : Configuration.Http.SecureHost;
+            m.Headers.Host = withPort ? Configuration.Http.SecureHost + ":" + Configuration.Http.SecurePort : Configuration.Http.SecureHost;
 
             using (HttpClient client = CreateHttpClient())
             using (HttpResponseMessage response = await client.SendAsync(TestAsync, m))
@@ -372,8 +377,9 @@ public async Task SendAsync_GetWithValidHostHeader_Success(bool withPort)
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [Fact]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/53874", TestPlatforms.Browser)]
         public async Task SendAsync_GetWithInvalidHostHeader_ThrowsException()
         {
             if (LoopbackServerFactory.Version >= HttpVersion.Version20)

src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientTest.cs

@@ -1213,10 +1213,10 @@ public async Task SendAsync_CorrectVersionSelected_LoopbackServer(Version reques
                 });
         }
 
+        [Theory]
         [OuterLoop("Uses external servers")]
         [MemberData(nameof(VersionSelectionMemberData))]
-        [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsBrowserDomSupportedOrNotBrowser))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/53018", TestPlatforms.Browser)]
+        [SkipOnPlatform(TestPlatforms.Browser, "Version is ignored on Browser")]
         public async Task SendAsync_CorrectVersionSelected_ExternalServer(Version requestVersion, HttpVersionPolicy versionPolicy, Version serverVersion, bool useSsl, object expectedResult)
         {
             RemoteServer remoteServer = null;

src/libraries/System.Net.Http/tests/FunctionalTests/System.Net.Http.Functional.Tests.csproj

@@ -8,11 +8,19 @@
     <IncludeRemoteExecutor>true</IncludeRemoteExecutor>
     <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-Linux;$(NetCoreAppCurrent)-Browser;$(NetCoreAppCurrent)-OSX</TargetFrameworks>
   </PropertyGroup>
+
   <PropertyGroup Condition="'$(TargetOS)' == 'Browser'">
     <Scenario>WasmTestOnBrowser</Scenario>
     <TestArchiveTestsRoot>$(TestArchiveRoot)browseronly/</TestArchiveTestsRoot>
     <TestArchiveTestsDir>$(TestArchiveTestsRoot)$(OSPlatformConfig)/</TestArchiveTestsDir>
   </PropertyGroup>
+
+  <Import Condition="'$(TargetOS)' == 'Browser'" Project="$(CommonTestPath)System/Net/Prerequisites/LocalEchoServer.props" />
+
+  <ItemGroup Condition="'$(TargetOS)' == 'Browser'">
+    <ProjectReference Include="$(CommonTestPath)System/Net/Prerequisites/NetCoreServer/NetCoreServer.csproj" ReferenceOutputAssembly="false"/>
+  </ItemGroup>
+
   <ItemGroup>
     <Compile Include="$(CommonPath)Interop\Unix\Interop.Libraries.cs" Condition="'$(TargetsUnix)' == 'true' or '$(TargetsBrowser)' == 'true'"
              Link="Common\Interop\Unix\Interop.Libraries.cs" />

src/libraries/System.Net.WebSockets.Client/tests/CancelTest.cs

@@ -13,7 +13,7 @@ public class CancelTest : ClientWebSocketTestBase
     {
         public CancelTest(ITestOutputHelper output) : base(output) { }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task ConnectAsync_Cancel_ThrowsCancellationException(Uri server)
         {
@@ -29,7 +29,7 @@ public async Task ConnectAsync_Cancel_ThrowsCancellationException(Uri server)
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task SendAsync_Cancel_Success(Uri server)
         {
@@ -44,7 +44,7 @@ public async Task SendAsync_Cancel_Success(Uri server)
             }, server);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/19217")]
         public async Task ReceiveAsync_Cancel_Success(Uri server)
@@ -67,7 +67,7 @@ public async Task ReceiveAsync_Cancel_Success(Uri server)
             }, server);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseAsync_Cancel_Success(Uri server)
         {
@@ -89,7 +89,7 @@ public async Task CloseAsync_Cancel_Success(Uri server)
             }, server);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseOutputAsync_Cancel_Success(Uri server)
         {
@@ -112,7 +112,7 @@ public async Task CloseOutputAsync_Cancel_Success(Uri server)
             }, server);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task ReceiveAsync_CancelThenReceive_ThrowsOperationCanceledException(Uri server)
         {
@@ -128,7 +128,7 @@ public async Task ReceiveAsync_CancelThenReceive_ThrowsOperationCanceledExceptio
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task ReceiveAsync_ReceiveThenCancel_ThrowsOperationCanceledException(Uri server)
         {
@@ -144,7 +144,7 @@ public async Task ReceiveAsync_ReceiveThenCancel_ThrowsOperationCanceledExceptio
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task ReceiveAsync_AfterCancellationDoReceiveAsync_ThrowsWebSocketException(Uri server)
         {

src/libraries/System.Net.WebSockets.Client/tests/CloseTest.cs

@@ -18,7 +18,7 @@ public class CloseTest : ClientWebSocketTestBase
         public CloseTest(ITestOutputHelper output) : base(output) { }
 
         [ActiveIssue("https://github.com/dotnet/runtime/issues/28957")]
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServersAndBoolean))]
         public async Task CloseAsync_ServerInitiatedClose_Success(Uri server, bool useCloseOutputAsync)
         {
@@ -65,7 +65,7 @@ public async Task CloseAsync_ServerInitiatedClose_Success(Uri server, bool useCl
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseAsync_ClientInitiatedClose_Success(Uri server)
         {
@@ -87,7 +87,7 @@ public async Task CloseAsync_ClientInitiatedClose_Success(Uri server)
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseAsync_CloseDescriptionIsMaxLength_Success(Uri server)
         {
@@ -101,7 +101,7 @@ public async Task CloseAsync_CloseDescriptionIsMaxLength_Success(Uri server)
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseAsync_CloseDescriptionIsMaxLengthPlusOne_ThrowsArgumentException(Uri server)
         {
@@ -126,7 +126,7 @@ public async Task CloseAsync_CloseDescriptionIsMaxLengthPlusOne_ThrowsArgumentEx
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseAsync_CloseDescriptionHasUnicode_Success(Uri server)
         {
@@ -145,7 +145,7 @@ public async Task CloseAsync_CloseDescriptionHasUnicode_Success(Uri server)
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseAsync_CloseDescriptionIsNull_Success(Uri server)
         {
@@ -161,7 +161,7 @@ public async Task CloseAsync_CloseDescriptionIsNull_Success(Uri server)
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseOutputAsync_ExpectedStates(Uri server)
         {
@@ -180,7 +180,7 @@ public async Task CloseOutputAsync_ExpectedStates(Uri server)
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseAsync_CloseOutputAsync_Throws(Uri server)
         {
@@ -205,7 +205,7 @@ public async Task CloseAsync_CloseOutputAsync_Throws(Uri server)
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseOutputAsync_ClientInitiated_CanReceive_CanClose(Uri server)
         {
@@ -245,7 +245,7 @@ public async Task CloseOutputAsync_ClientInitiated_CanReceive_CanClose(Uri serve
         }
 
         [ActiveIssue("https://github.com/dotnet/runtime/issues/28957")]
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseOutputAsync_ServerInitiated_CanSend(Uri server)
         {
@@ -292,7 +292,7 @@ public async Task CloseOutputAsync_ServerInitiated_CanSend(Uri server)
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseOutputAsync_CloseDescriptionIsNull_Success(Uri server)
         {
@@ -308,7 +308,7 @@ public async Task CloseOutputAsync_CloseDescriptionIsNull_Success(Uri server)
         }
 
         [ActiveIssue("https://github.com/dotnet/runtime/issues/22000", TargetFrameworkMonikers.Netcoreapp)]
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseOutputAsync_DuringConcurrentReceiveAsync_ExpectedStates(Uri server)
         {
@@ -345,7 +345,7 @@ public async Task CloseOutputAsync_DuringConcurrentReceiveAsync_ExpectedStates(U
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task CloseAsync_DuringConcurrentReceiveAsync_ExpectedStates(Uri server)
         {

src/libraries/System.Net.WebSockets.Client/tests/ConnectTest.cs

@@ -17,7 +17,7 @@ public class ConnectTest : ClientWebSocketTestBase
         public ConnectTest(ITestOutputHelper output) : base(output) { }
 
         [ActiveIssue("https://github.com/dotnet/runtime/issues/1895")]
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(UnavailableWebSocketServers))]
         public async Task ConnectAsync_NotWebSocketServer_ThrowsWebSocketExceptionWithMessage(Uri server, string exceptionMessage, WebSocketError errorCode)
         {
@@ -42,21 +42,21 @@ public async Task ConnectAsync_NotWebSocketServer_ThrowsWebSocketExceptionWithMe
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task EchoBinaryMessage_Success(Uri server)
         {
             await WebSocketHelper.TestEcho(server, WebSocketMessageType.Binary, TimeOutMilliseconds, _output);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task EchoTextMessage_Success(Uri server)
         {
             await WebSocketHelper.TestEcho(server, WebSocketMessageType.Text, TimeOutMilliseconds, _output);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoHeadersServers))]
         [SkipOnPlatform(TestPlatforms.Browser, "CustomHeaders not supported on browser")]
         public async Task ConnectAsync_AddCustomHeaders_Success(Uri server)
@@ -118,7 +118,7 @@ public async Task ConnectAsync_AddHostHeader_Success()
             }), new LoopbackServer.Options { WebSocketEndpoint = true });
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoHeadersServers))]
         [SkipOnPlatform(TestPlatforms.Browser, "Cookies not supported on browser")]
         public async Task ConnectAsync_CookieHeaders_Success(Uri server)
@@ -168,7 +168,7 @@ public async Task ConnectAsync_CookieHeaders_Success(Uri server)
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/45583", TestPlatforms.Browser)]
         public async Task ConnectAsync_PassNoSubProtocol_ServerRequires_ThrowsWebSocketException(Uri server)
@@ -194,7 +194,7 @@ public async Task ConnectAsync_PassNoSubProtocol_ServerRequires_ThrowsWebSocketE
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task ConnectAsync_PassMultipleSubProtocols_ServerRequires_ConnectionUsesAgreedSubProtocol(Uri server)
         {
@@ -235,7 +235,7 @@ public async Task ConnectAsync_NonStandardRequestHeaders_HeadersAddedWithoutVali
             }), new LoopbackServer.Options { WebSocketEndpoint = true });
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/42852", TestPlatforms.Browser)]
         public async Task ConnectAndCloseAsync_UseProxyServer_ExpectedClosedState(Uri server)

src/libraries/System.Net.WebSockets.Client/tests/SendReceiveTest.cs

@@ -49,7 +49,7 @@ public abstract class SendReceiveTest : ClientWebSocketTestBase
 
         public SendReceiveTest(ITestOutputHelper output) : base(output) { }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task SendReceive_PartialMessageDueToSmallReceiveBuffer_Success(Uri server)
         {
@@ -86,7 +86,7 @@ public async Task SendReceive_PartialMessageDueToSmallReceiveBuffer_Success(Uri
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         [SkipOnPlatform(TestPlatforms.Browser, "JS Websocket does not support see issue https://github.com/dotnet/runtime/issues/46983")]
         public async Task SendReceive_PartialMessageBeforeCompleteMessageArrives_Success(Uri server)
@@ -128,7 +128,7 @@ public async Task SendReceive_PartialMessageBeforeCompleteMessageArrives_Success
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task SendAsync_SendCloseMessageType_ThrowsArgumentExceptionWithMessage(Uri server)
         {
@@ -156,7 +156,7 @@ public async Task SendAsync_SendCloseMessageType_ThrowsArgumentExceptionWithMess
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task SendAsync_MultipleOutstandingSendOperations_Throws(Uri server)
         {
@@ -215,7 +215,7 @@ public async Task SendAsync_MultipleOutstandingSendOperations_Throws(Uri server)
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task ReceiveAsync_MultipleOutstandingReceiveOperations_Throws(Uri server)
         {
@@ -279,7 +279,7 @@ public async Task ReceiveAsync_MultipleOutstandingReceiveOperations_Throws(Uri s
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task SendAsync_SendZeroLengthPayloadAsEndOfMessage_Success(Uri server)
         {
@@ -318,7 +318,7 @@ public async Task SendAsync_SendZeroLengthPayloadAsEndOfMessage_Success(Uri serv
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task SendReceive_VaryingLengthBuffers_Success(Uri server)
         {
@@ -358,7 +358,7 @@ public async Task SendReceive_VaryingLengthBuffers_Success(Uri server)
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task SendReceive_Concurrent_Success(Uri server)
         {
@@ -387,7 +387,7 @@ public async Task SendReceive_Concurrent_Success(Uri server)
             }
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalFact(nameof(WebSocketsSupported))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/42852", TestPlatforms.Browser)]
         public async Task SendReceive_ConnectionClosedPrematurely_ReceiveAsyncFailsAndWebSocketStateUpdated()
@@ -457,7 +457,7 @@ public async Task SendReceive_ConnectionClosedPrematurely_ReceiveAsyncFailsAndWe
             }, options);
         }
 
-        [OuterLoop("Uses external servers")]
+        [OuterLoop("Uses external servers", typeof(PlatformDetection), nameof(PlatformDetection.LocalEchoServerIsNotAvailable))]
         [ConditionalTheory(nameof(WebSocketsSupported)), MemberData(nameof(EchoServers))]
         public async Task ZeroByteReceive_CompletesWhenDataAvailable(Uri server)
         {

src/libraries/System.Net.WebSockets.Client/tests/System.Net.WebSockets.Client.Tests.csproj

@@ -4,11 +4,19 @@
     <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppCurrent)-Browser</TargetFrameworks>
     <DefineConstants>$(DefineConstants);NETSTANDARD</DefineConstants>
   </PropertyGroup>
+
   <PropertyGroup Condition="'$(TargetOS)' == 'Browser'">
     <Scenario>WasmTestOnBrowser</Scenario>
     <TestArchiveTestsRoot>$(TestArchiveRoot)browseronly/</TestArchiveTestsRoot>
     <TestArchiveTestsDir>$(TestArchiveTestsRoot)$(OSPlatformConfig)/</TestArchiveTestsDir>
   </PropertyGroup>
+
+  <Import Condition="'$(TargetOS)' == 'Browser'" Project="$(CommonTestPath)System/Net/Prerequisites/LocalEchoServer.props" />
+
+  <ItemGroup Condition="'$(TargetOS)' == 'Browser'">
+    <ProjectReference Include="$(CommonTestPath)System/Net/Prerequisites/NetCoreServer/NetCoreServer.csproj" ReferenceOutputAssembly="false"/>
+  </ItemGroup>
+
   <!-- Do not reference these assemblies from the TargetingPack since we are building part of the source code for tests. -->
   <ItemGroup>
     <DefaultReferenceExclusion Include="System.Configuration" />

src/libraries/sendtohelixhelp.proj

@@ -297,6 +297,7 @@
       <SeleniumUrl>https://storage.googleapis.com/chromium-browser-snapshots/Linux_x64/$(ChromiumRevision)/chromedriver_linux64.zip</SeleniumUrl>
       <EmSdkDir>$([MSBuild]::NormalizeDirectory('$(RepoRoot)', 'src', 'mono', 'wasm', 'emsdk'))</EmSdkDir>
       <WasmBuildTargetsDir>$([MSBuild]::NormalizeDirectory('$(RepoRoot)', 'src', 'mono', 'wasm', 'build'))</WasmBuildTargetsDir>
+      <TestEchoMiddleware>$([MSBuild]::NormalizeDirectory('$(ArtifactsDir)', 'bin', 'NetCoreServer', '$(NetCoreAppCurrent)-$(Configuration)'))</TestEchoMiddleware>
     </PropertyGroup>
 
     <PropertyGroup Condition="'$(RuntimeFlavor)' == 'Mono'">
@@ -329,6 +330,10 @@
       <HelixCorrelationPayload Include="$(MonoAotCrossDir)"                      Destination="build/cross" />
     </ItemGroup>
 
+    <ItemGroup Condition="'$(TargetOS)' == 'Browser'">
+      <HelixCorrelationPayload Include="$(TestEchoMiddleware)" Destination="xharness/TestEchoMiddleware" />
+    </ItemGroup>
+
     <ItemGroup Condition="'$(TargetOS)' != 'Android' and '$(TargetOS)' != 'iOS' and '$(TargetOS)' != 'iOSSimulator' and '$(TargetOS)' != 'tvOS' and '$(TargetOS)' != 'tvOSSimulator' and '$(TargetOS)' != 'MacCatalyst'">
       <HelixCorrelationPayload Include="$(HelixCorrelationPayload)"
                                Condition="'$(IncludeHelixCorrelationPayload)' == 'true' and '$(TargetOS)' != 'Browser'" />