Add a test that we're not enabling the GIL.

Author: jamadden

.github/workflows/tests.yml

@@ -107,7 +107,7 @@ jobs:
       run: |
         sphinx-build -b doctest -d docs/_build/doctrees2 docs docs/_build/doctest2
     - name: Lint
-      if: matrix.python-version == '3.12' && startsWith(runner.os, 'Linux')
+      if: matrix.python-version == '3.14' && startsWith(runner.os, 'Linux')
       # We only need to do this on one version.
       # We do this here rather than a separate job to avoid the compilation overhead.
       run: |

src/greenlet/tests/test_greenlet.py

@@ -1349,5 +1349,16 @@ def test_reentrant_switch_run_callable_has_del(self):
             output
         )
 
+class TestModule(TestCase):
+
+    @unittest.skipUnless(hasattr(sys, '_is_gil_enabled'),
+                         "Needs 3.13 and above for sys._is_gil_enabled")
+    def test_no_gil_on_free_threaded(self):
+
+        if RUNNING_ON_FREETHREAD_BUILD:
+            self.assertFalse(sys._is_gil_enabled())
+        else:
+            self.assertTrue(sys._is_gil_enabled())
+
 if __name__ == '__main__':
     unittest.main()