Fix AspNetCoreServer tests surfaced by unit-test auto-discovery

These test projects were never run in CI before the discovery change, so
pre-existing failures went unnoticed. Fixes by category:

Real test bugs (failed deterministically, incl. locally):
- BuildStreamingPreludeTests / ResponseStreamingPropertyTests: the
  StandalonePreludeBuilder subclassed the HTTP API v2 function (whose
  BuildStreamingPrelude override collapses headers into single-value
  Headers), but the tests assert on the multi-value MultiValueHeaders
  collection. Derive from the REST v1 APIGatewayProxyFunction instead,
  matching the assertions and the section comments.

CI-environment robustness (passed locally, failed in CI):
- ci.buildspec.yml: raise fs.inotify.max_user_instances (container
  default 128 was exhausted once all ASP.NET-host-starting unit tests
  run, surfacing as inotify IOExceptions across ~90 tests).
- TestMinimalAPI: capture child-process stdout/stderr and handle the
  WaitForExit timeout so the out-of-process 'dotnet run' failure
  (exit 129) is diagnosable and the process cannot leak.
- AddAWSLambdaBeforeSnapshotRequestTests: poll for the before-snapshot
  callback instead of racing a fixed 500 ms delay that was flaky under
  CI load.

Author: GarrettBeatty

Libraries/test/Amazon.Lambda.AspNetCoreServer.Hosting.Tests/AddAWSLambdaBeforeSnapshotRequestTests.cs

@@ -44,10 +44,16 @@ public async Task VerifyCallbackIsInvoked(LambdaEventSource hostingType)
 
         var serverTask = app.RunAsync();
 
-        // let the server run for a max of 500 ms
-        await Task.WhenAny(
-            serverTask,
-            Task.Delay(TimeSpan.FromMilliseconds(500)));
+        // Poll for the before-snapshot callback to fire rather than racing a single fixed delay.
+        // A fixed 500 ms window is flaky under load (observed intermittently in CI): the
+        // before-snapshot request may not have completed yet, leaving the callback unset. Wait up
+        // to 10 seconds, checking frequently, and stop as soon as the callback has run.
+        var timeout = TimeSpan.FromSeconds(10);
+        var sw = System.Diagnostics.Stopwatch.StartNew();
+        while (!callbackDidTheCallback && sw.Elapsed < timeout && !serverTask.IsCompleted)
+        {
+            await Task.Delay(TimeSpan.FromMilliseconds(50));
+        }
 
         // shut down server
         await app.StopAsync();

Libraries/test/Amazon.Lambda.AspNetCoreServer.Test/BuildStreamingPreludeTests.cs

@@ -14,7 +14,10 @@ public class BuildStreamingPreludeTests
     {
         // Subclass that skips host startup entirely and
         // just exposes BuildStreamingPrelude directly without needing a running host.
-        private class StandalonePreludeBuilder : APIGatewayHttpApiV2ProxyFunction
+        // Derives from the REST (v1) APIGatewayProxyFunction because these tests assert on the
+        // multi-value MultiValueHeaders collection; the HTTP API v2 function instead collapses
+        // headers into the single-value Headers collection (see APIGatewayHttpApiV2ProxyFunction).
+        private class StandalonePreludeBuilder : APIGatewayProxyFunction
         {
             // Use the StartupMode.FirstRequest constructor so no host is started eagerly.
             public StandalonePreludeBuilder()

Libraries/test/Amazon.Lambda.AspNetCoreServer.Test/ResponseStreamingPropertyTests.cs

@@ -71,7 +71,10 @@ protected override APIGatewayHttpApiV2ProxyResponse MarshallResponse(
             }
         }
 
-        private class StandalonePreludeBuilder : APIGatewayHttpApiV2ProxyFunction
+        // Derives from the REST (v1) APIGatewayProxyFunction because the prelude property tests
+        // (Property3/Property4) assert on the multi-value MultiValueHeaders collection; the HTTP
+        // API v2 function instead collapses headers into the single-value Headers collection.
+        private class StandalonePreludeBuilder : APIGatewayProxyFunction
         {
             public StandalonePreludeBuilder() : base(StartupMode.FirstRequest) { }
 

Libraries/test/Amazon.Lambda.AspNetCoreServer.Test/TestMinimalAPI.cs

@@ -54,16 +54,32 @@ public T ExecuteRequest<T>(string eventFilePath)
                 processStartInfo.FileName = GetSystemShell();
                 processStartInfo.Arguments = $"{comamndArgument} dotnet run \"{requestFilePath}\" \"{responseFilePath}\"";
                 processStartInfo.WorkingDirectory = GetTestAppDirectory();
+                // Capture the child process output so a launch/build failure (e.g. the exit code 129
+                // seen intermittently in CI) surfaces a diagnosable message instead of a bare exit code.
+                processStartInfo.RedirectStandardOutput = true;
+                processStartInfo.RedirectStandardError = true;
+                processStartInfo.UseShellExecute = false;
 
 
                 lock (lock_process)
                 {
                     using var process = Process.Start(processStartInfo);
-                    process.WaitForExit(15000);
+                    var stdout = process.StandardOutput.ReadToEndAsync();
+                    var stderr = process.StandardError.ReadToEndAsync();
+
+                    // WaitForExit(timeout) returns false when the process is still running at the
+                    // timeout; kill it so it does not leak, then fail with the captured output.
+                    if (!process.WaitForExit(60000))
+                    {
+                        process.Kill(entireProcessTree: true);
+                        throw new Exception(
+                            $"Process timed out after 60s.{Environment.NewLine}STDOUT:{Environment.NewLine}{stdout.Result}{Environment.NewLine}STDERR:{Environment.NewLine}{stderr.Result}");
+                    }
 
                     if (process.ExitCode != 0)
                     {
-                        throw new Exception("Process failed with exit code: " + process.ExitCode);
+                        throw new Exception(
+                            $"Process failed with exit code: {process.ExitCode}.{Environment.NewLine}STDOUT:{Environment.NewLine}{stdout.Result}{Environment.NewLine}STDERR:{Environment.NewLine}{stderr.Result}");
                     }
 
                     if(!File.Exists(responseFilePath))

buildtools/ci.buildspec.yml

@@ -5,6 +5,12 @@ phases:
     runtime-versions:
       dotnet: 8.x
     commands:
+      # Raise the inotify limits. The AspNetCoreServer tests each start an ASP.NET Core host, and the
+      # file-watching config providers allocate inotify instances; the container default (128) is
+      # exhausted once all unit-test projects run, surfacing as
+      # "The configured user limit (128) on the number of inotify instances has been reached".
+      - sysctl -w fs.inotify.max_user_instances=1024 || true
+      - sysctl -w fs.inotify.max_user_watches=524288 || true
       # Find and delete the global.json files that were added by CodeBuild. This causes issues when multiple SDKs are installed.
       - find / -type f -name 'global.json' -delete
       # The tests need .NET 3.1, 6, 8, 9 and 10. .NET6 is installed by default. .NET8 is added in the runtime-versions. .NET 3.1, 9 and 10 are installed manually.