Move StreamClientTransport tests into StdioClientTransportTests

Per review feedback, consolidate stream client transport tests into
StdioClientTransportTests.cs for consistency with how StreamServerTransport
tests live in StdioServerTransportTests.cs.

Co-authored-by: halter73 <54385+halter73@users.noreply.github.com>

Author: Copilot

tests/ModelContextProtocol.Tests/Transport/StdioClientTransportTests.cs

@@ -1,14 +1,17 @@
 using ModelContextProtocol.Client;
 using ModelContextProtocol.Protocol;
 using ModelContextProtocol.Tests.Utils;
+using System.IO.Pipelines;
 using System.Runtime.InteropServices;
 using System.Text;
+using System.Text.Json;
 
 namespace ModelContextProtocol.Tests.Transport;
 
 public class StdioClientTransportTests(ITestOutputHelper testOutputHelper) : LoggedTest(testOutputHelper)
 {
     public static bool IsStdErrCallbackSupported => !PlatformDetection.IsMonoRuntime;
+    public static bool IsWindows => PlatformDetection.IsWindows;
 
     [Fact]
     public async Task CreateAsync_ValidProcessInvalidServer_Throws()
@@ -136,4 +139,54 @@ public async Task EscapesCliArgumentsCorrectly(string? cliArgumentValue)
         var content = Assert.IsType<TextContentBlock>(Assert.Single(result.Content));
         Assert.Equal(cliArgumentValue ?? "", content.Text);
     }
+
+    [Fact]
+    public async Task SendMessageAsync_Should_Use_LF_Not_CRLF()
+    {
+        using var serverInput = new MemoryStream();
+        Pipe serverOutputPipe = new();
+
+        var transport = new StreamClientTransport(serverInput, serverOutputPipe.Reader.AsStream(), LoggerFactory);
+        await using var sessionTransport = await transport.ConnectAsync(TestContext.Current.CancellationToken);
+
+        var message = new JsonRpcRequest { Method = "test", Id = new RequestId(44) };
+
+        await sessionTransport.SendMessageAsync(message, TestContext.Current.CancellationToken);
+
+        byte[] bytes = serverInput.ToArray();
+
+        // The output should end with exactly \n (0x0A), not \r\n (0x0D 0x0A).
+        Assert.True(bytes.Length > 1, "Output should contain message data");
+        Assert.Equal((byte)'\n', bytes[^1]);
+        Assert.NotEqual((byte)'\r', bytes[^2]);
+
+        // Also verify the JSON content is valid
+        var json = Encoding.UTF8.GetString(bytes).TrimEnd('\n');
+        var expected = JsonSerializer.Serialize(message, McpJsonUtilities.DefaultOptions);
+        Assert.Equal(expected, json);
+    }
+
+    [Fact(Skip = "Non-Windows platform", SkipUnless = nameof(IsWindows))]
+    public async Task ReadMessagesAsync_Should_Accept_CRLF_Delimited_Messages()
+    {
+        Pipe serverInputPipe = new();
+        Pipe serverOutputPipe = new();
+
+        var transport = new StreamClientTransport(serverInputPipe.Writer.AsStream(), serverOutputPipe.Reader.AsStream(), LoggerFactory);
+        await using var sessionTransport = await transport.ConnectAsync(TestContext.Current.CancellationToken);
+
+        var message = new JsonRpcRequest { Method = "test", Id = new RequestId(44) };
+        var json = JsonSerializer.Serialize(message, McpJsonUtilities.DefaultOptions);
+
+        // Write a \r\n-delimited message to the server's output (which the client reads)
+        await serverOutputPipe.Writer.WriteAsync(Encoding.UTF8.GetBytes($"{json}\r\n"), TestContext.Current.CancellationToken);
+
+        var canRead = await sessionTransport.MessageReader.WaitToReadAsync(TestContext.Current.CancellationToken);
+
+        Assert.True(canRead, "Should be able to read a \\r\\n-delimited message");
+        Assert.True(sessionTransport.MessageReader.TryPeek(out var readMessage));
+        Assert.NotNull(readMessage);
+        Assert.IsType<JsonRpcRequest>(readMessage);
+        Assert.Equal("44", ((JsonRpcRequest)readMessage).Id.ToString());
+    }
 }