[release/7.0] Throw on incompatible WebSocket options

src/libraries/System.Net.WebSockets.Client/src/Resources/Strings.resx

@@ -129,4 +129,10 @@
   <data name="net_WebSockets_ClientWindowBitsNegotiationFailure" xml:space="preserve">
     <value>The WebSocket failed to negotiate max client window bits. The client requested {0} but the server responded with {1}.</value>
   </data>
+  <data name="net_WebSockets_OptionsIncompatibleWithCustomInvoker" xml:space="preserve">
+    <value>UseDefaultCredentials, Credentials, Proxy, ClientCertificates, RemoteCertificateValidationCallback and Cookies must not be set on ClientWebSocketOptions when an HttpMessageInvoker instance is also specified. These options should be set on the HttpMessageInvoker's underlying HttpMessageHandler instead.</value>
+  </data>
+  <data name="net_WebSockets_CustomInvokerRequiredForHttp2" xml:space="preserve">
+    <value>An HttpMessageInvoker instance must be passed to ConnectAsync when using HTTP/2.</value>
+  </data>
 </root>

src/libraries/System.Net.WebSockets.Client/src/System/Net/WebSockets/ClientWebSocketOptions.cs

@@ -30,6 +30,14 @@ public sealed class ClientWebSocketOptions
         private HttpVersionPolicy _versionPolicy = HttpVersionPolicy.RequestVersionOrLower;
         private bool _collectHttpResponseDetails;
 
+        internal bool AreCompatibleWithCustomInvoker() =>
+            !UseDefaultCredentials &&
+            Credentials is null &&
+            (_clientCertificates?.Count ?? 0) == 0 &&
+            RemoteCertificateValidationCallback is null &&
+            Cookies is null &&
+            (Proxy is null || Proxy == WebSocketHandle.DefaultWebProxy.Instance);
+
         internal ClientWebSocketOptions() { } // prevent external instantiation
 
         #region HTTP Settings

src/libraries/System.Net.WebSockets.Client/src/System/Net/WebSockets/WebSocketHandle.Managed.cs

@@ -48,9 +48,22 @@ public void Abort()
         public async Task ConnectAsync(Uri uri, HttpMessageInvoker? invoker, CancellationToken cancellationToken, ClientWebSocketOptions options)
         {
             bool disposeHandler = false;
-            invoker ??= new HttpMessageInvoker(SetupHandler(options, out disposeHandler));
-            HttpResponseMessage? response = null;
+            if (invoker is null)
+            {
+                if (options.HttpVersion.Major >= 2 || options.HttpVersionPolicy == HttpVersionPolicy.RequestVersionOrHigher)
+                {
+                    throw new ArgumentException(SR.net_WebSockets_CustomInvokerRequiredForHttp2, nameof(options));
+                }
 
+                invoker = new HttpMessageInvoker(SetupHandler(options, out disposeHandler));
+            }
+            else if (!options.AreCompatibleWithCustomInvoker())
+            {
+                // This will not throw if the Proxy is a DefaultWebProxy.
+                throw new ArgumentException(SR.net_WebSockets_OptionsIncompatibleWithCustomInvoker, nameof(options));
+            }
+
+            HttpResponseMessage? response = null;
             bool disposeResponse = false;
 
             // force non-secure request to 1.1 whenever it is possible as HttpClient does
@@ -237,12 +250,7 @@ private static SocketsHttpHandler SetupHandler(ClientWebSocketOptions options, o
             // Create the handler for this request and populate it with all of the options.
             // Try to use a shared handler rather than creating a new one just for this request, if
             // the options are compatible.
-            if (options.Credentials == null &&
-                !options.UseDefaultCredentials &&
-                options.Proxy == null &&
-                options.Cookies == null &&
-                options.RemoteCertificateValidationCallback == null &&
-                (options._clientCertificates?.Count ?? 0) == 0)
+            if (options.AreCompatibleWithCustomInvoker() && options.Proxy is null)
             {
                 disposeHandler = false;
                 handler = s_defaultHandler;
@@ -518,7 +526,7 @@ private static void ValidateHeader(HttpHeaders headers, string name, string expe
         }
 
         /// <summary>Used as a sentinel to indicate that ClientWebSocket should use the system's default proxy.</summary>
-        private sealed class DefaultWebProxy : IWebProxy
+        internal sealed class DefaultWebProxy : IWebProxy
         {
             public static DefaultWebProxy Instance { get; } = new DefaultWebProxy();
             public ICredentials? Credentials { get => throw new NotSupportedException(); set => throw new NotSupportedException(); }

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

@@ -16,14 +16,14 @@ public sealed class InvokerAbortTest : AbortTest
     {
         public InvokerAbortTest(ITestOutputHelper output) : base(output) { }
 
-        protected override HttpMessageInvoker? GetInvoker() => new HttpMessageInvoker(new SocketsHttpHandler());
+        protected override bool UseCustomInvoker => true;
     }
 
     public sealed class HttpClientAbortTest : AbortTest
     {
         public HttpClientAbortTest(ITestOutputHelper output) : base(output) { }
 
-        protected override HttpMessageInvoker? GetInvoker() => new HttpClient(new HttpClientHandler());
+        protected override bool UseHttpClient => true;
     }
 
     public class AbortTest : ClientWebSocketTestBase

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

@@ -14,14 +14,14 @@ public sealed class InvokerCancelTest : CancelTest
     {
         public InvokerCancelTest(ITestOutputHelper output) : base(output) { }
 
-        protected override HttpMessageInvoker? GetInvoker() => new HttpMessageInvoker(new SocketsHttpHandler());
+        protected override bool UseCustomInvoker => true;
     }
 
     public sealed class HttpClientCancelTest : CancelTest
     {
         public HttpClientCancelTest(ITestOutputHelper output) : base(output) { }
 
-        protected override HttpMessageInvoker? GetInvoker() => new HttpClient(new HttpClientHandler());
+        protected override bool UseHttpClient => true;
     }
 
     public class CancelTest : ClientWebSocketTestBase

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

@@ -2,21 +2,17 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections.Generic;
-using System.Net.Test.Common;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 
 using Xunit;
 using Xunit.Abstractions;
 using System.Net.Http;
-using System.Net.WebSockets.Client.Tests;
+using System.Diagnostics;
 
 namespace System.Net.WebSockets.Client.Tests
 {
-    /// <summary>
-    /// ClientWebSocket tests that do require a remote server.
-    /// </summary>
     public class ClientWebSocketTestBase
     {
         public static readonly object[][] EchoServers = System.Net.Test.Common.Configuration.WebSockets.EchoServers;
@@ -112,7 +108,38 @@ protected static async Task<WebSocketReceiveResult> ReceiveEntireMessageAsync(We
             }
         }
 
-        protected virtual HttpMessageInvoker? GetInvoker() => null;
+        protected virtual bool UseCustomInvoker => false;
+
+        protected virtual bool UseHttpClient => false;
+
+        protected bool UseSharedHandler => !UseCustomInvoker && !UseHttpClient;
+
+        protected Action<HttpClientHandler>? ConfigureCustomHandler;
+
+        internal HttpMessageInvoker? GetInvoker()
+        {
+            var handler = new HttpClientHandler();
+
+            if (PlatformDetection.IsNotBrowser)
+            {
+                handler.ServerCertificateCustomValidationCallback = HttpClientHandler.DangerousAcceptAnyServerCertificateValidator;
+            }
+
+            ConfigureCustomHandler?.Invoke(handler);
+
+            if (UseCustomInvoker)
+            {
+                Debug.Assert(!UseHttpClient);
+                return new HttpMessageInvoker(handler);
+            }
+
+            if (UseHttpClient)
+            {
+                return new HttpClient(handler);
+            }
+
+            return null;
+        }
 
         protected Task<ClientWebSocket> GetConnectedWebSocket(Uri uri, int TimeOutMilliseconds, ITestOutputHelper output) =>
             WebSocketHelper.GetConnectedWebSocket(uri, TimeOutMilliseconds, output, invoker: GetInvoker());

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

@@ -18,14 +18,14 @@ public sealed class InvokerCloseTest : CloseTest
     {
         public InvokerCloseTest(ITestOutputHelper output) : base(output) { }
 
-        protected override HttpMessageInvoker? GetInvoker() => new HttpMessageInvoker(new SocketsHttpHandler());
+        protected override bool UseCustomInvoker => true;
     }
 
     public sealed class HttpClientCloseTest : CloseTest
     {
         public HttpClientCloseTest(ITestOutputHelper output) : base(output) { }
 
-        protected override HttpMessageInvoker? GetInvoker() => new HttpClient(new HttpClientHandler());
+        protected override bool UseHttpClient => true;
     }
 
     public class CloseTest : ClientWebSocketTestBase