Python: do not report an unreachable Redis as a missing index

python/semantic_kernel/connectors/redis.py

@@ -17,6 +17,7 @@
 from redis.commands.search.field import Field as RedisField
 from redis.commands.search.field import NumericField, TagField, TextField, VectorField
 from redis.commands.search.index_definition import IndexDefinition, IndexType
+from redis.exceptions import ResponseError
 from redisvl.index.index import process_results
 from redisvl.query.filter import FilterExpression, Num, Tag, Text
 from redisvl.query.query import BaseQuery, VectorQuery
@@ -287,7 +288,13 @@ async def collection_exists(self, **kwargs) -> bool:
         try:
             await self.redis_database.ft(self.collection_name).info()
             return True
-        except Exception:
+        except ResponseError:
+            # Redis answers FT.INFO for an unknown index with an error reply, which redis-py
+            # surfaces as ResponseError. ConnectionError, TimeoutError and AuthenticationError are
+            # siblings of ResponseError rather than subclasses, so they now propagate instead of
+            # being reported as "the index is not there". ensure_collection_deleted() gates the
+            # drop on this answer, so a swallowed timeout made it return successfully having
+            # deleted nothing.
             return False
 
     @override

python/tests/unit/connectors/memory/test_redis_store.py

@@ -5,6 +5,8 @@
 import numpy as np
 from pytest import fixture, mark, raises
 from redis.asyncio.client import Redis
+from redis.exceptions import ConnectionError as RedisConnectionError
+from redis.exceptions import ResponseError
 
 from semantic_kernel.connectors.redis import (
     RedisCollectionTypes,
@@ -281,11 +283,24 @@ async def test_collection_exists(collection_hash, mock_collection_exists):
 
 
 async def test_collection_exists_false(collection_hash, mock_collection_exists):
-    mock_collection_exists.side_effect = Exception
+    # ResponseError is what redis-py raises when FT.INFO reports an unknown index. The previous
+    # bare Exception did not represent that, and matched a timeout just as readily.
+    mock_collection_exists.side_effect = ResponseError("Unknown Index name")
     exists = await collection_hash.collection_exists()
     assert not exists
 
 
+async def test_collection_exists_propagates_connection_errors(collection_hash, mock_collection_exists):
+    """A cluster that cannot be reached is not an absent index.
+
+    ensure_collection_deleted() drops the index only when collection_exists() says it is there, so
+    reporting a connection failure as "not there" made the delete a silent no-op.
+    """
+    mock_collection_exists.side_effect = RedisConnectionError("connection refused")
+    with raises(RedisConnectionError):
+        await collection_hash.collection_exists()
+
+
 async def test_ensure_collection_deleted(collection_hash, mock_ensure_collection_deleted):
     await collection_hash.ensure_collection_deleted()
     await collection_hash.ensure_collection_deleted()