[WIP] IFrameworkHandle.LaunchProcessWithDebuggerAttached allows null for workingDirectory in signature but throws (#15091)

* Initial plan for issue

* Fix LaunchProcessWithDebuggerAttached to handle null workingDirectory

Co-authored-by: nohwnd <[email protected]>

* Update documentation for workingDirectory parameter to clarify null behavior

Co-authored-by: nohwnd <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: nohwnd <[email protected]>

Author: Copilot

src/Microsoft.TestPlatform.CrossPlatEngine/Adapter/FrameworkHandle.cs

@@ -65,7 +65,7 @@ public FrameworkHandle(ITestCaseEventsHandler? testCaseEventsHandler, ITestRunCa
     /// Launch the specified process with the debugger attached.
     /// </summary>
     /// <param name="filePath">File path to the exe to launch.</param>
-    /// <param name="workingDirectory">Working directory that process should use.</param>
+    /// <param name="workingDirectory">Working directory that process should use. If null, the current directory will be used.</param>
     /// <param name="arguments">Command line arguments the process should be launched with.</param>
     /// <param name="environmentVariables">Environment variables to be set in target process</param>
     /// <returns>Process ID of the started process.</returns>
@@ -89,7 +89,7 @@ public int LaunchProcessWithDebuggerAttached(string filePath, string? workingDir
             Arguments = arguments,
             EnvironmentVariables = environmentVariables,
             FileName = filePath,
-            WorkingDirectory = workingDirectory
+            WorkingDirectory = workingDirectory ?? Environment.CurrentDirectory
         };
 
         return _testRunEventsHandler.LaunchProcessWithDebuggerAttached(processInfo);

src/Microsoft.TestPlatform.ObjectModel/Adapter/Interfaces/IFrameworkHandle.cs

@@ -23,7 +23,7 @@ public interface IFrameworkHandle : ITestExecutionRecorder, IMessageLogger
     /// Launch the specified process with the debugger attached.
     /// </summary>
     /// <param name="filePath">File path to the exe to launch.</param>
-    /// <param name="workingDirectory">Working directory that process should use.</param>
+    /// <param name="workingDirectory">Working directory that process should use. If null, the current directory will be used.</param>
     /// <param name="arguments">Command line arguments the process should be launched with.</param>
     /// <param name="environmentVariables">Environment variables to be set in target process</param>
     /// <returns>Process ID of the started process.</returns>

test/Microsoft.TestPlatform.CrossPlatEngine.UnitTests/Adapter/FrameworkHandleTests.cs

@@ -87,6 +87,57 @@ public void LaunchProcessWithDebuggerAttachedShouldCallRunEventsHandler()
             mt.LaunchProcessWithDebuggerAttached(It.IsAny<TestProcessStartInfo>()), Times.Once);
     }
 
+    [TestMethod]
+    public void LaunchProcessWithDebuggerAttachedShouldSetCurrentDirectoryWhenWorkingDirectoryIsNull()
+    {
+        var tec = GetTestExecutionContext();
+        tec.IsDebug = true;
+        var mockTestRunEventsHandler = new Mock<IInternalTestRunEventsHandler>();
+        TestProcessStartInfo? capturedProcessInfo = null;
+
+        mockTestRunEventsHandler
+            .Setup(mt => mt.LaunchProcessWithDebuggerAttached(It.IsAny<TestProcessStartInfo>()))
+            .Callback<TestProcessStartInfo>(info => capturedProcessInfo = info)
+            .Returns(1234);
+
+        var frameworkHandle = new FrameworkHandle(
+            null,
+            new TestRunCache(100, TimeSpan.MaxValue, (s, r, ip) => { }),
+            tec,
+            mockTestRunEventsHandler.Object);
+
+        frameworkHandle.LaunchProcessWithDebuggerAttached("test.exe", null, null, null);
+
+        Assert.IsNotNull(capturedProcessInfo);
+        Assert.AreEqual(Environment.CurrentDirectory, capturedProcessInfo.WorkingDirectory);
+    }
+
+    [TestMethod]
+    public void LaunchProcessWithDebuggerAttachedShouldUseProvidedWorkingDirectory()
+    {
+        var tec = GetTestExecutionContext();
+        tec.IsDebug = true;
+        var mockTestRunEventsHandler = new Mock<IInternalTestRunEventsHandler>();
+        TestProcessStartInfo? capturedProcessInfo = null;
+        var expectedWorkingDirectory = "/custom/path";
+
+        mockTestRunEventsHandler
+            .Setup(mt => mt.LaunchProcessWithDebuggerAttached(It.IsAny<TestProcessStartInfo>()))
+            .Callback<TestProcessStartInfo>(info => capturedProcessInfo = info)
+            .Returns(1234);
+
+        var frameworkHandle = new FrameworkHandle(
+            null,
+            new TestRunCache(100, TimeSpan.MaxValue, (s, r, ip) => { }),
+            tec,
+            mockTestRunEventsHandler.Object);
+
+        frameworkHandle.LaunchProcessWithDebuggerAttached("test.exe", expectedWorkingDirectory, null, null);
+
+        Assert.IsNotNull(capturedProcessInfo);
+        Assert.AreEqual(expectedWorkingDirectory, capturedProcessInfo.WorkingDirectory);
+    }
+
     private static TestExecutionContext GetTestExecutionContext()
     {
         var tec = new TestExecutionContext(