Fix hanging of NamedPipeClientStream when connecting with infinite timeout

src/libraries/System.IO.Pipes/src/System/IO/Pipes/NamedPipeClientStream.cs

@@ -135,7 +135,7 @@ private void ConnectInternal(int timeout, CancellationToken cancellationToken, i
                 cancellationToken.ThrowIfCancellationRequested();
 
                 // Determine how long we should wait in this connection attempt
-                int waitTime = timeout - elapsed;
+                int waitTime = timeout == Timeout.Infinite ? CancellationCheckInterval : timeout - elapsed;
                 if (cancellationToken.CanBeCanceled && waitTime > CancellationCheckInterval)
                 {
                     waitTime = CancellationCheckInterval;

src/libraries/System.IO.Pipes/tests/NamedPipeTests/NamedPipeTest.Specific.cs

@@ -664,6 +664,31 @@ public async Task ClientConnectAsync_With_Cancellation_Throws_Timeout_When_Pipe_
             }
         }
 
+        [Fact]
+        [PlatformSpecific(TestPlatforms.Windows)] // Unix implementation doesn't rely on a timeout and cancellation token when connecting
+        public async Task ClientConnectAsync_Cancel_With_InfiniteTimeout()
+        {
+            string pipeName = PipeStreamConformanceTests.GetUniquePipeName();
+
+            using (var cts = new CancellationTokenSource())
+            using (var server = new NamedPipeServerStream(pipeName, PipeDirection.InOut, 1))
+            using (var firstClient = new NamedPipeClientStream(pipeName))
+            using (var secondClient = new NamedPipeClientStream(pipeName))
+            {
+                var firstConnectionTasks = new Task[]
+                    {
+                        firstClient.ConnectAsync(),
+                        Task.Run(() => server.WaitForConnectionAsync())
+                    };
+
+                Assert.True(Task.WaitAll(firstConnectionTasks, 1000));
+
+                cts.CancelAfter(100);
+
+                await Assert.ThrowsAsync<OperationCanceledException>(() => secondClient.ConnectAsync(cts.Token)).WaitAsync(1000);
+            }
+        }
+
         public static IEnumerable<object[]> GetCancellationTokens =>
             new []
             {