Flip stdin and stdout in StreamClientTransport

Author: halter73

tests/ModelContextProtocol.Tests/Client/McpClientExtensionsTests.cs

@@ -38,8 +38,8 @@ private async Task<IMcpClient> CreateMcpClientForServer()
     {
         await _server.StartAsync(TestContext.Current.CancellationToken);
 
-        var stdin = new StreamReader(_serverToClientPipe.Reader.AsStream());
-        var stdout = new StreamWriter(_clientToServerPipe.Writer.AsStream());
+        var stdin = new StreamWriter(_clientToServerPipe.Writer.AsStream());
+        var stdout = new StreamReader(_serverToClientPipe.Reader.AsStream());
 
         var serverConfig = new McpServerConfig()
         {

tests/ModelContextProtocol.Tests/Configuration/McpServerBuilderExtensionsToolsTests.cs

@@ -48,8 +48,8 @@ private async Task<IMcpClient> CreateMcpClientForServer()
     {
         await _server.StartAsync(TestContext.Current.CancellationToken);
 
-        var stdin = new StreamReader(_serverToClientPipe.Reader.AsStream());
-        var stdout = new StreamWriter(_clientToServerPipe.Writer.AsStream());
+        var stdin = new StreamWriter(_clientToServerPipe.Writer.AsStream());
+        var stdout = new StreamReader(_serverToClientPipe.Reader.AsStream());
 
         var serverConfig = new McpServerConfig()
         {
@@ -124,7 +124,7 @@ public async Task Can_Create_Multiple_Servers_From_Options_And_List_Registered_T
 
                 var client = await McpClientFactory.CreateAsync(
                     serverConfig,
-                    createTransportFunc: (_, _) => new StreamClientTransport(stdout, stdin),
+                    createTransportFunc: (_, _) => new StreamClientTransport(stdin, stdout),
                     cancellationToken: TestContext.Current.CancellationToken);
 
                 var tools = await client.ListToolsAsync(TestContext.Current.CancellationToken);

tests/ModelContextProtocol.Tests/Transport/StreamClientTransport.cs

@@ -11,14 +11,14 @@ internal sealed class StreamClientTransport : TransportBase, IClientTransport
     private readonly JsonSerializerOptions _jsonOptions = McpJsonUtilities.DefaultOptions;
     private Task? _readTask;
     private CancellationTokenSource _shutdownCts = new CancellationTokenSource();
-    private readonly TextReader _stdin;
-    private readonly TextWriter _stdout;
+    private readonly TextReader _stdout;
+    private readonly TextWriter _stdin;
 
-    public StreamClientTransport(TextReader stdin, TextWriter stdout)
+    public StreamClientTransport(TextWriter stdin, TextReader stdout)
         : base(NullLoggerFactory.Instance)
     {
-        _stdin = stdin;
         _stdout = stdout;
+        _stdin = stdin;
         _readTask = Task.Run(() => ReadMessagesAsync(_shutdownCts.Token), CancellationToken.None);
         SetConnected(true);
     }
@@ -31,13 +31,13 @@ public override async Task SendMessageAsync(IJsonRpcMessage message, Cancellatio
             messageWithId.Id.ToString() :
             "(no id)";
 
-        await _stdout.WriteLineAsync(JsonSerializer.Serialize(message)).ConfigureAwait(false);
-        await _stdout.FlushAsync(cancellationToken).ConfigureAwait(false);
+        await _stdin.WriteLineAsync(JsonSerializer.Serialize(message)).ConfigureAwait(false);
+        await _stdin.FlushAsync(cancellationToken).ConfigureAwait(false);
     }
 
     private async Task ReadMessagesAsync(CancellationToken cancellationToken)
     {
-        while (await _stdin.ReadLineAsync(cancellationToken).ConfigureAwait(false) is string line)
+        while (await _stdout.ReadLineAsync(cancellationToken).ConfigureAwait(false) is string line)
         {
             if (!string.IsNullOrWhiteSpace(line))
             {