gh-139951: Test on GC collection disabled if threshold is zero (GH-140304)

diff --git a/Lib/test/test_gc.py b/Lib/test/test_gc.py
index 4328909053465eaf2dc0a75c61de9ed6145be510..70d9d009fa8bfdfb80b62717ff68d26ea206eba6 100644 (file)
--- a/Lib/test/test_gc.py
+++ b/Lib/test/test_gc.py
@@ -1559,6 +1559,20 @@ class GCTogglingTests(unittest.TestCase):
         finally:
             gc.enable()
 
+    # Ensure that setting *threshold0* to zero disables collection.
+    @gc_threshold(0)
+    def test_threshold_zero(self):
+        junk = []
+        i = 0
+        detector = GC_Detector()
+        while not detector.gc_happened:
+            i += 1
+            if i > 50000:
+                break
+            junk.append([])  # this may eventually trigger gc (if it is enabled)
+
+        self.assertEqual(i, 50001)
+
 
 class PythonFinalizationTests(unittest.TestCase):
     def test_ast_fini(self):