Resolve test suite execution import errors due to path ordering (micr…

…osoft/vscode-python#23099)

- This has already been discussed and resolved for tests discovery in
this [PR](microsoft/vscode-python#22454)
- I have now run into the same issue for executing the test suite and
have applied the same fix in this PR
- Tested and working

[Issue](microsoft/vscode-python#23098) for
this current PR

[Original
Issue](microsoft/vscode-python#22453)
[Original PR](microsoft/vscode-python#22454)

Co-authored-by: Eleanor Boyd <eleanorboyd@microsoft.com>

extensions/positron-python/python_files/unittestadapter/execution.py

@@ -171,6 +171,11 @@ def run_tests(
     locals: Optional[bool] = None,
 ) -> PayloadDict:
     cwd = os.path.abspath(start_dir)
+    if "/" in start_dir:  #  is a subdir
+        parent_dir = os.path.dirname(start_dir)
+        sys.path.insert(0, parent_dir)
+    else:
+        sys.path.insert(0, cwd)
     status = TestExecutionStatus.error
     error = None
     payload: PayloadDict = {"cwd": cwd, "status": status, "result": None}