Resolved race condition during Redis backend teardown (#418)

src/pytest_celery/vendors/redis/backend/api.py

@@ -8,16 +8,30 @@
 
 import gc
 
+from celery.result import AsyncResult
+
 from pytest_celery.api.backend import CeleryTestBackend
 
 
 class RedisTestBackend(CeleryTestBackend):
     def teardown(self) -> None:
-        # When a test that has a AsyncResult object is finished
-        # there's a race condition between the AsyncResult object
-        # and the Redis container. The AsyncResult object tries
-        # to release the connection but the Redis container has already
-        # exited. This causes a warning to be logged. To avoid this
-        # warning to our best effort we force a garbage collection here.
-        gc.collect(1)
+        """When a test that has a AsyncResult object is finished there's a race
+        condition between the AsyncResult object and the Redis container.
+
+        The AsyncResult object tries to release the connection but the
+        Redis container has already exited.
+        """
+        # First, force a garbage collection to clean up unreachable objects
+        gc.collect()
+
+        # Next, find all live AsyncResult objects and clean them up
+        async_results = [obj for obj in gc.get_objects() if isinstance(obj, AsyncResult)]
+
+        for async_result in async_results:
+            try:
+                # Remove the backend reference to prevent interaction with Redis
+                async_result.backend = None
+            except Exception:
+                pass
+
         super().teardown()