Reduce flakiness in long-running stateless HTTP tool timeout test (#1300)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: halter73 <54385+halter73@users.noreply.github.com>

Author: Copilot

tests/ModelContextProtocol.AspNetCore.Tests/MapMcpTests.cs

@@ -245,34 +245,49 @@ public async Task LongRunningToolCall_DoesNotTimeout_WhenNoEventStreamStore()
         app.MapMcp();
         await app.StartAsync(TestContext.Current.CancellationToken);
 
-        // Create a custom HttpClient with a very short timeout (1 second)
-        // The tool will take 2 seconds to complete
-        using var shortTimeoutClient = new HttpClient(SocketsHttpHandler)
+        // Retry a couple of times to reduce occasional flakiness on low-resource machines.
+        // If the server regresses to flushing only after tool completion, each attempt should still fail
+        // because HttpClient timeout (1 second) is below the tool duration (2 seconds).
+        for (var attempt = 0; attempt < 3; attempt++)
         {
-            BaseAddress = new Uri("http://localhost:5000/"),
-            Timeout = TimeSpan.FromSeconds(1)
-        };
-
-        var path = UseStreamableHttp ? "/" : "/sse";
-        var transportMode = UseStreamableHttp ? HttpTransportMode.StreamableHttp : HttpTransportMode.Sse;
-
-        await using var transport = new HttpClientTransport(new()
-        {
-            Endpoint = new($"http://localhost:5000{path}"),
-            TransportMode = transportMode,
-        }, shortTimeoutClient, LoggerFactory);
+            try
+            {
+                // Create a custom HttpClient with a very short timeout (1 second)
+                // The tool will take 2 seconds to complete
+                using var shortTimeoutClient = new HttpClient(SocketsHttpHandler, disposeHandler: false)
+                {
+                    BaseAddress = new Uri("http://localhost:5000/"),
+                    Timeout = TimeSpan.FromSeconds(1)
+                };
 
-        await using var mcpClient = await McpClient.CreateAsync(transport, loggerFactory: LoggerFactory, cancellationToken: TestContext.Current.CancellationToken);
+                var path = UseStreamableHttp ? "/" : "/sse";
+                var transportMode = UseStreamableHttp ? HttpTransportMode.StreamableHttp : HttpTransportMode.Sse;
 
-        // Call a tool that takes 2 seconds - this should succeed despite the 1 second HttpClient timeout
-        // because the response stream is flushed immediately after receiving the request
-        var response = await mcpClient.CallToolAsync(
-            "long_running_operation",
-            new Dictionary<string, object?>() { ["durationMs"] = 2000 },
-            cancellationToken: TestContext.Current.CancellationToken);
+                await using var transport = new HttpClientTransport(new()
+                {
+                    Endpoint = new($"http://localhost:5000{path}"),
+                    TransportMode = transportMode,
+                }, shortTimeoutClient, LoggerFactory);
+
+                await using var mcpClient = await McpClient.CreateAsync(transport, loggerFactory: LoggerFactory, cancellationToken: TestContext.Current.CancellationToken);
+
+                // Call a tool that takes 2 seconds - this should succeed despite the 1 second HttpClient timeout
+                // because the response stream is flushed immediately after receiving the request
+                var response = await mcpClient.CallToolAsync(
+                    "long_running_operation",
+                    new Dictionary<string, object?>() { ["durationMs"] = 2000 },
+                    cancellationToken: TestContext.Current.CancellationToken);
+
+                var content = Assert.Single(response.Content.OfType<TextContentBlock>());
+                Assert.Equal("Operation completed after 2000ms", content.Text);
+                return;
+            }
+            catch (OperationCanceledException) when (attempt < 2)
+            {
+                // Retry intermittent timeout-related failures on slow CI machines.
+            }
+        }
 
-        var content = Assert.Single(response.Content.OfType<TextContentBlock>());
-        Assert.Equal("Operation completed after 2000ms", content.Text);
     }
 
     private ClaimsPrincipal CreateUser(string name)