Use LoggedTest.LoggerFactory and MockLoggerProvider in trace logging tests

Simplified the tests by using the base class's LoggerFactory and MockLoggerProvider
instead of creating local instances. The LoggerFactory is overridden in the constructor
to use LogLevel.Trace for the trace logging tests.

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

Author: Copilot

tests/ModelContextProtocol.Tests/Transport/StdioServerTransportTests.cs

@@ -22,6 +22,14 @@ public StdioServerTransportTests(ITestOutputHelper testOutputHelper)
             InitializationTimeout = TimeSpan.FromSeconds(10),
             ServerInstructions = "Test Instructions"
         };
+
+        // Override the LoggerFactory to use Trace level for testing Trace-level logging
+        LoggerFactory = Microsoft.Extensions.Logging.LoggerFactory.Create(builder =>
+        {
+            builder.AddProvider(XunitLoggerProvider);
+            builder.AddProvider(MockLoggerProvider);
+            builder.SetMinimumLevel(LogLevel.Trace);
+        });
     }
 
     [Fact(Skip="https://github.com/modelcontextprotocol/csharp-sdk/issues/143")]
@@ -199,25 +207,19 @@ public async Task SendMessageAsync_Should_Preserve_Unicode_Characters()
     public async Task SendMessageAsync_Should_Log_At_Trace_Level()
     {
         // Arrange
-        var mockLoggerProvider = new MockLoggerProvider();
-        using var traceLoggerFactory = Microsoft.Extensions.Logging.LoggerFactory.Create(builder =>
-        {
-            builder.AddProvider(mockLoggerProvider);
-            builder.SetMinimumLevel(LogLevel.Trace);
-        });
         using var output = new MemoryStream();
 
         await using var transport = new StreamServerTransport(
             new Pipe().Reader.AsStream(),
             output,
-            loggerFactory: traceLoggerFactory);
+            loggerFactory: LoggerFactory);
 
         // Act
         var message = new JsonRpcRequest { Method = "test", Id = new RequestId(44) };
         await transport.SendMessageAsync(message, TestContext.Current.CancellationToken);
 
         // Assert
-        var traceLogMessages = mockLoggerProvider.LogMessages
+        var traceLogMessages = MockLoggerProvider.LogMessages
             .Where(x => x.LogLevel == LogLevel.Trace && x.Message.Contains("transport sending message"))
             .ToList();
 
@@ -229,13 +231,6 @@ public async Task SendMessageAsync_Should_Log_At_Trace_Level()
     public async Task ReadMessagesAsync_Should_Log_Received_At_Trace_Level()
     {
         // Arrange
-        var mockLoggerProvider = new MockLoggerProvider();
-        using var traceLoggerFactory = Microsoft.Extensions.Logging.LoggerFactory.Create(builder =>
-        {
-            builder.AddProvider(mockLoggerProvider);
-            builder.SetMinimumLevel(LogLevel.Trace);
-        });
-
         var message = new JsonRpcRequest { Method = "test", Id = new RequestId(99) };
         var json = JsonSerializer.Serialize(message, McpJsonUtilities.DefaultOptions);
 
@@ -245,7 +240,7 @@ public async Task ReadMessagesAsync_Should_Log_Received_At_Trace_Level()
         await using var transport = new StreamServerTransport(
             input,
             Stream.Null,
-            loggerFactory: traceLoggerFactory);
+            loggerFactory: LoggerFactory);
 
         // Act
         await pipe.Writer.WriteAsync(Encoding.UTF8.GetBytes($"{json}\n"), TestContext.Current.CancellationToken);
@@ -255,7 +250,7 @@ public async Task ReadMessagesAsync_Should_Log_Received_At_Trace_Level()
         Assert.True(canRead, "Nothing to read here from transport message reader");
 
         // Assert
-        var traceLogMessages = mockLoggerProvider.LogMessages
+        var traceLogMessages = MockLoggerProvider.LogMessages
             .Where(x => x.LogLevel == LogLevel.Trace && x.Message.Contains("transport received message"))
             .ToList();