add hook to the pytest vscode plugin to determine how many xdist work…

…ers to use based on how many tests are selected

python_files/vscode_pytest/__init__.py

@@ -8,15 +8,15 @@
 import sys
 import traceback
 
-
+from pluggy import Result
 import pytest
 
 script_dir = pathlib.Path(__file__).parent.parent
 sys.path.append(os.fspath(script_dir))
 sys.path.append(os.fspath(script_dir / "lib" / "python"))
 
 from testing_tools import socket_manager  # noqa: E402
-from typing import Any, Dict, List, Optional, Union, TypedDict, Literal  # noqa: E402
+from typing import Any, Dict, Generator, List, Optional, Union, TypedDict, Literal  # noqa: E402
 
 
 class TestData(TypedDict):
@@ -881,3 +881,9 @@ def send_post_request(
             f"Plugin error, exception thrown while attempting to send data[vscode-pytest]: {error} \n[vscode-pytest] data: \n{data}\n",
             file=sys.stderr,
         )
+
+
+@pytest.hookimpl(hookwrapper=True)
+def pytest_xdist_auto_num_workers(config: pytest.Config) -> Generator[None, Result[int], int]:
+    """determine how many workers to use based on how many tests were selected in the test explorer"""
+    return min((yield).get_result(), len(config.option.file_or_dir))