self.assertRaises causes an allocation, so the _testcapi call

has been moved to immediately before the _channels.create()
call to ensure we correctly target the allocation failure.

Author: stestagg

Lib/test/test_interpreters/test_channels.py

@@ -38,9 +38,9 @@ def test_lock_allocation_failure(self):
         import _testcapi
 
         cid = None
-        _testcapi.set_nomemory(0, 1)
         try:
             with self.assertRaises(MemoryError):
+                _testcapi.set_nomemory(0, 1)
                 cid = _channels.create()
         finally:
             _testcapi.remove_mem_hooks()