add test for GIL

Author: fedemengo

tests/test_free_threaded.py

@@ -0,0 +1,21 @@
+import os
+import subprocess
+import sys
+
+import pytest
+
+
+def _is_freethreaded_build():
+    import sysconfig
+    return bool(sysconfig.get_config_var("Py_GIL_DISABLED"))
+
+
+@pytest.mark.skipif(not _is_freethreaded_build(), reason="requires free-threaded Python build")
+def test_evdev_does_not_reenable_gil():
+    result = subprocess.run(
+        [sys.executable, "-c", "import sys; import evdev; assert not sys._is_gil_enabled()"],
+        capture_output=True,
+        text=True,
+        env={**os.environ, "PYTHON_GIL": "0"},
+    )
+    assert result.returncode == 0, f"evdev re-enabled the GIL:\n{result.stderr}"