1 files changed, 48 insertions, 1 deletions
diff --git a/Lib/test/test_gc.py b/Lib/test/test_gc.py
index 9788291..100c767 100644
--- a/Lib/test/test_gc.py
+++ b/Lib/test/test_gc.py
@@ -1,5 +1,5 @@
 import unittest
-from test.support import verbose, run_unittest
+from test.support import verbose, run_unittest, strip_python_stderr
 import sys
 import gc
 import weakref
@@ -477,6 +477,53 @@ class GCTests(unittest.TestCase):
             # would be damaged, with an empty __dict__.
             self.assertEqual(x, None)
 
+    def test_garbage_at_shutdown(self):
+        import subprocess
+        code = """if 1:
+            import gc
+            class X:
+                def __init__(self, name):
+                    self.name = name
+                def __repr__(self):
+                    return "<X %%r>" %% self.name
+                def __del__(self):
+                    pass
+
+            x = X('first')
+            x.x = x
+            x.y = X('second')
+            del x
+            gc.set_debug(%s)
+        """
+        def run_command(code):
+            p = subprocess.Popen([sys.executable, "-Wd", "-c", code],
+                stdout=subprocess.PIPE,
+                stderr=subprocess.PIPE)
+            stdout, stderr = p.communicate()
+            p.stdout.close()
+            p.stderr.close()
+            self.assertEqual(p.returncode, 0)
+            self.assertEqual(stdout.strip(), b"")
+            return strip_python_stderr(stderr)
+
+        stderr = run_command(code % "0")
+        self.assertIn(b"ResourceWarning: gc: 2 uncollectable objects at "
+                      b"shutdown; use", stderr)
+        self.assertNotIn(b"<X 'first'>", stderr)
+        # With DEBUG_UNCOLLECTABLE, the garbage list gets printed
+        stderr = run_command(code % "gc.DEBUG_UNCOLLECTABLE")
+        self.assertIn(b"ResourceWarning: gc: 2 uncollectable objects at "
+                      b"shutdown", stderr)
+        self.assertTrue(
+            (b"[<X 'first'>, <X 'second'>]" in stderr) or
+            (b"[<X 'second'>, <X 'first'>]" in stderr), stderr)
+        # With DEBUG_SAVEALL, no additional message should get printed
+        # (because gc.garbage also contains normally reclaimable cyclic
+        # references, and its elements get printed at runtime anyway).
+        stderr = run_command(code % "gc.DEBUG_SAVEALL")
+        self.assertNotIn(b"uncollectable objects at shutdown", stderr)
+
+
 class GCTogglingTests(unittest.TestCase):
     def setUp(self):
         gc.enable()