Add ability to wait for debugger attach (#4829)

Author: Evangelink

src/Platform/Microsoft.Testing.Platform/Builder/TestApplication.cs

@@ -73,17 +73,18 @@ public static async Task<ITestApplicationBuilder> CreateBuilderAsync(string[] ar
         string createBuilderEntryTime = createBuilderStart.ToString("HH:mm:ss.fff", CultureInfo.InvariantCulture);
         testApplicationOptions ??= new TestApplicationOptions();
 
-        LaunchAttachDebugger(systemEnvironment);
+        SystemConsole systemConsole = new();
+        SystemProcessHandler systemProcess = new();
+        AttachDebuggerIfNeeded(systemEnvironment, systemConsole, systemProcess);
 
         // First step is to parse the command line from where we get the second input layer.
         // The first one should be the env vars handled autonomously by extensions and part of the test platform.
         CommandLineParseResult parseResult = CommandLineParser.Parse(args, systemEnvironment);
         TestHostControllerInfo testHostControllerInfo = new(parseResult);
-        SystemProcessHandler systemProcess = new();
         CurrentTestApplicationModuleInfo testApplicationModuleInfo = new(systemEnvironment, systemProcess);
 
         // Create the UnhandledExceptionHandler that will be set inside the TestHostBuilder.
-        LazyInitializer.EnsureInitialized(ref s_unhandledExceptionHandler, () => new UnhandledExceptionHandler(systemEnvironment, new SystemConsole(), parseResult.IsOptionSet(PlatformCommandLineProvider.TestHostControllerPIDOptionKey)));
+        LazyInitializer.EnsureInitialized(ref s_unhandledExceptionHandler, () => new UnhandledExceptionHandler(systemEnvironment, systemConsole, parseResult.IsOptionSet(PlatformCommandLineProvider.TestHostControllerPIDOptionKey)));
         ApplicationStateGuard.Ensure(s_unhandledExceptionHandler is not null);
 
         // First task is to setup the logger if enabled and we take the info from the command line or env vars.
@@ -234,12 +235,25 @@ public ValueTask DisposeAsync()
     public async Task<int> RunAsync()
         => await _testHost.RunAsync();
 
-    private static void LaunchAttachDebugger(SystemEnvironment environment)
+    private static void AttachDebuggerIfNeeded(SystemEnvironment environment, SystemConsole console, SystemProcessHandler systemProcess)
     {
         if (environment.GetEnvironmentVariable(EnvironmentVariableConstants.TESTINGPLATFORM_LAUNCH_ATTACH_DEBUGGER) == "1")
         {
             Debugger.Launch();
         }
+
+        if (environment.GetEnvironmentVariable(EnvironmentVariableConstants.TESTINGPLATFORM_WAIT_ATTACH_DEBUGGER) == "1")
+        {
+            IProcess currentProcess = systemProcess.GetCurrentProcess();
+            console.WriteLine($"Waiting for debugger to attach... Process Id: {currentProcess.Id}, Name: {currentProcess.Name}");
+
+            while (!Debugger.IsAttached)
+            {
+                Thread.Sleep(1000);
+            }
+
+            Debugger.Break();
+        }
     }
 
     /*

src/Platform/Microsoft.Testing.Platform/Helpers/EnvironmentVariableConstants.cs

@@ -32,6 +32,7 @@ internal static class EnvironmentVariableConstants
 
     // Debugging
     public const string TESTINGPLATFORM_LAUNCH_ATTACH_DEBUGGER = nameof(TESTINGPLATFORM_LAUNCH_ATTACH_DEBUGGER);
+    public const string TESTINGPLATFORM_WAIT_ATTACH_DEBUGGER = nameof(TESTINGPLATFORM_WAIT_ATTACH_DEBUGGER);
 
     // dotnet test
     public const string TESTINGPLATFORM_DOTNETTEST_EXECUTIONID = nameof(TESTINGPLATFORM_DOTNETTEST_EXECUTIONID);

src/Platform/Microsoft.Testing.Platform/Helpers/System/IProcess.cs

@@ -5,11 +5,14 @@ namespace Microsoft.Testing.Platform.Helpers;
 
 internal interface IProcess : IDisposable
 {
-    public event EventHandler Exited;
+    event EventHandler Exited;
 
     /// <inheritdoc cref="System.Diagnostics.Process.Id" />
     int Id { get; }
 
+    /// <inheritdoc cref="System.Diagnostics.Process.ProcessName" />
+    string Name { get; }
+
     /// <inheritdoc cref="System.Diagnostics.Process.ExitCode" />
     int ExitCode { get; }
 

src/Platform/Microsoft.Testing.Platform/Helpers/System/SystemProcess.cs

@@ -19,6 +19,8 @@ public SystemProcess(Process process)
 
     public int Id => _process.Id;
 
+    public string Name => _process.ProcessName;
+
     public int ExitCode => _process.ExitCode;
 
 #if NETCOREAPP