gh-117478: Add @support.requires_gil_enabled decorator (#117479)

Co-authored-by: Kirill Podoprigora <[email protected]>

Author: colesbury

Doc/library/test.rst

@@ -731,6 +731,12 @@ The :mod:`test.support` module defines the following functions:
    macOS version is less than the minimum, the test is skipped.
 
 
+.. decorator:: requires_gil_enabled
+
+   Decorator for skipping tests on the free-threaded build.  If the
+   :term:`GIL` is disabled, the test is skipped.
+
+
 .. decorator:: requires_IEEE_754
 
    Decorator for skipping tests on non-IEEE 754 platforms.

Lib/test/support/__init__.py

@@ -29,7 +29,7 @@
     "captured_stdin", "captured_stderr",
     # unittest
     "is_resource_enabled", "requires", "requires_freebsd_version",
-    "requires_linux_version", "requires_mac_ver",
+    "requires_gil_enabled", "requires_linux_version", "requires_mac_ver",
     "check_syntax_error",
     "requires_gzip", "requires_bz2", "requires_lzma",
     "bigmemtest", "bigaddrspacetest", "cpython_only", "get_attribute",
@@ -837,6 +837,11 @@ def check_cflags_pgo():
 
 
 Py_GIL_DISABLED = bool(sysconfig.get_config_var('Py_GIL_DISABLED'))
+
+def requires_gil_enabled(msg="needs the GIL enabled"):
+    """Decorator for skipping tests on the free-threaded build."""
+    return unittest.skipIf(Py_GIL_DISABLED, msg)
+
 if Py_GIL_DISABLED:
     _header = 'PHBBInP'
 else:

Lib/test/test_capi/test_mem.py

@@ -152,8 +152,8 @@ class C(): pass
             self.assertGreaterEqual(count, i*10-4)
 
 
-# Py_GIL_DISABLED requires mimalloc (not malloc)
-@unittest.skipIf(support.Py_GIL_DISABLED, 'need malloc')
+# free-threading requires mimalloc (not malloc)
+@support.requires_gil_enabled
 class PyMemMallocDebugTests(PyMemDebugTests):
     PYTHONMALLOC = 'malloc_debug'
 

Lib/test/test_cext/__init__.py

@@ -40,11 +40,11 @@ def test_build_c11(self):
     def test_build_c99(self):
         self.check_build('_test_c99_cext', std='c99')
 
-    @unittest.skipIf(support.Py_GIL_DISABLED, 'incompatible with Free Threading')
+    @support.requires_gil_enabled('incompatible with Free Threading')
     def test_build_limited(self):
         self.check_build('_test_limited_cext', limited=True)
 
-    @unittest.skipIf(support.Py_GIL_DISABLED, 'broken for now with Free Threading')
+    @support.requires_gil_enabled('broken for now with Free Threading')
     def test_build_limited_c11(self):
         self.check_build('_test_limited_c11_cext', limited=True, std='c11')
 

Lib/test/test_concurrent_futures/test_process_pool.py

@@ -116,7 +116,7 @@ def test_saturation(self):
         for _ in range(job_count):
             sem.release()
 
-    @unittest.skipIf(support.Py_GIL_DISABLED, "gh-117344: test is flaky without the GIL")
+    @support.requires_gil_enabled("gh-117344: test is flaky without the GIL")
     def test_idle_process_reuse_one(self):
         executor = self.executor
         assert executor._max_workers >= 4

Lib/test/test_concurrent_futures/test_thread_pool.py

@@ -41,7 +41,7 @@ def acquire_lock(lock):
             sem.release()
         executor.shutdown(wait=True)
 
-    @unittest.skipIf(support.Py_GIL_DISABLED, "gh-117344: test is flaky without the GIL")
+    @support.requires_gil_enabled("gh-117344: test is flaky without the GIL")
     def test_idle_thread_reuse(self):
         executor = self.executor_type()
         executor.submit(mul, 21, 2).result()

Lib/test/test_gc.py

@@ -1,7 +1,8 @@
 import unittest
 import unittest.mock
 from test.support import (verbose, refcount_test,
-                          cpython_only, requires_subprocess, Py_GIL_DISABLED)
+                          cpython_only, requires_subprocess,
+                          requires_gil_enabled)
 from test.support.import_helper import import_module
 from test.support.os_helper import temp_dir, TESTFN, unlink
 from test.support.script_helper import assert_python_ok, make_script
@@ -362,7 +363,7 @@ def __del__(self):
     # To minimize variations, though, we first store the get_count() results
     # and check them at the end.
     @refcount_test
-    @unittest.skipIf(Py_GIL_DISABLED, 'needs precise allocation counts')
+    @requires_gil_enabled('needs precise allocation counts')
     def test_get_count(self):
         gc.collect()
         a, b, c = gc.get_count()
@@ -815,7 +816,7 @@ def test_get_objects(self):
                 any(l is element for element in gc.get_objects())
         )
 
-    @unittest.skipIf(Py_GIL_DISABLED, 'need generational GC')
+    @requires_gil_enabled('need generational GC')
     def test_get_objects_generations(self):
         gc.collect()
         l = []
@@ -1046,7 +1047,7 @@ def setUp(self):
     def tearDown(self):
         gc.disable()
 
-    @unittest.skipIf(Py_GIL_DISABLED, "Free threading does not support incremental GC")
+    @requires_gil_enabled("Free threading does not support incremental GC")
     # Use small increments to emulate longer running process in a shorter time
     @gc_threshold(200, 10)
     def test_incremental_gc_handles_fast_cycle_creation(self):