[dotnet test MTP] Separate evaluation parallelization level from running test apps (#50805)

Author: Youssef1313

src/Cli/dotnet/Commands/Test/MTP/MSBuildUtility.cs

@@ -67,7 +67,7 @@ public static (IEnumerable<ParallelizableTestModuleGroupWithSequentialInnerModul
         return (projects, isBuiltOrRestored);
     }
 
-    public static BuildOptions GetBuildOptions(ParseResult parseResult, int degreeOfParallelism)
+    public static BuildOptions GetBuildOptions(ParseResult parseResult)
     {
         LoggerUtility.SeparateBinLogArguments(parseResult.UnmatchedTokens, out var binLogArgs, out var otherArgs);
 
@@ -106,7 +106,6 @@ public static BuildOptions GetBuildOptions(ParseResult parseResult, int degreeOf
             parseResult.HasOption(TestCommandParser.VerbosityOption) ? parseResult.GetValue(TestCommandParser.VerbosityOption) : null,
             parseResult.GetValue(MicrosoftTestingPlatformOptions.NoLaunchProfileOption),
             parseResult.GetValue(MicrosoftTestingPlatformOptions.NoLaunchProfileArgumentsOption),
-            degreeOfParallelism,
             otherArgs,
             msbuildArgs);
     }
@@ -137,7 +136,9 @@ private static ConcurrentBag<ParallelizableTestModuleGroupWithSequentialInnerMod
 
         Parallel.ForEach(
             projects,
-            new ParallelOptions { MaxDegreeOfParallelism = buildOptions.DegreeOfParallelism },
+            // We don't use --max-parallel-test-modules here.
+            // If user wants to limit the test applications run in parallel, we don't want to punish them and force the evaluation to also be limited.
+            new ParallelOptions { MaxDegreeOfParallelism = Environment.ProcessorCount },
             (project) =>
             {
                 IEnumerable<ParallelizableTestModuleGroupWithSequentialInnerModules> projectsMetadata = SolutionAndProjectUtility.GetProjectProperties(project, projectCollection, evaluationContext, buildOptions);

src/Cli/dotnet/Commands/Test/MTP/MicrosoftTestingPlatformTestCommand.cs

@@ -51,7 +51,7 @@ private int RunInternal(ParseResult parseResult, bool isHelp)
 
         SetupCancelKeyPressHandler();
 
-        BuildOptions buildOptions = MSBuildUtility.GetBuildOptions(parseResult, degreeOfParallelism);
+        BuildOptions buildOptions = MSBuildUtility.GetBuildOptions(parseResult);
 
         bool filterModeEnabled = parseResult.HasOption(MicrosoftTestingPlatformOptions.TestModulesFilterOption);
         TestApplicationActionQueue actionQueue;

src/Cli/dotnet/Commands/Test/MTP/Options.cs

@@ -14,6 +14,5 @@ internal record BuildOptions(
     Utils.VerbosityOptions? Verbosity,
     bool NoLaunchProfile,
     bool NoLaunchProfileArguments,
-    int DegreeOfParallelism,
     List<string> UnmatchedTokens,
     IEnumerable<string> MSBuildArgs);