[release/10.0.2xx] Adjust MTP exit code logic (#52543)

Co-authored-by: Youssef Victor <youssefvictor00@gmail.com>
dotnet · tmat · Jan 29, 2026 · Jan 16, 2026 · Jan 17, 2026 · Jan 17, 2026
commit e41a21bce785c606a970ac45a27c4bb0f86cade6
diff --git a/src/Cli/dotnet/Commands/Test/MTP/MicrosoftTestingPlatformTestCommand.cs b/src/Cli/dotnet/Commands/Test/MTP/MicrosoftTestingPlatformTestCommand.cs
@@ -80,7 +80,13 @@ private int RunInternal(ParseResult parseResult, bool isHelp)
        actionQueue.EnqueueCompleted();
        // Don't inline exitCode variable. We want to always call WaitAllActions first.
        var exitCode = actionQueue.WaitAllActions();
-        exitCode = _output.HasHandshakeFailure ? ExitCode.GenericFailure : exitCode;
+
+        // If all test apps exited with 0 exit code, but we detected that handshake didn't happen correctly, map that to generic failure.
+        if (exitCode == ExitCode.Success && _output.HasHandshakeFailure)
+        {
+            exitCode = ExitCode.GenericFailure;
+        }
+
        if (exitCode == ExitCode.Success &&
            parseResult.HasOption(definition.MinimumExpectedTestsOption) &&
            parseResult.GetValue(definition.MinimumExpectedTestsOption) is { } minimumExpectedTests &&