fix(collections): re-raise non-404 errors from async Collection.exists()

The async `Collection.exists()` still had a bare `except Exception: return
False`, so a connection error, auth failure or timeout was indistinguishable
from "collection not found". PR #1950 fixed this for the sync path only.

Mirror the sync implementation: return False on 404 and re-raise anything
else. Adds a mock test covering both branches on the async client.

Fixes #2100

Author: Anai-Guo

mock_tests/test_collection.py

@@ -484,6 +484,26 @@ def test_collection_exists(weaviate_mock: HTTPServer) -> None:
             assert e.value.status_code == 500
 
 
+@pytest.mark.asyncio
+async def test_async_collection_exists(weaviate_mock: HTTPServer) -> None:
+    non_existing = "NonExistingCollection"
+    erroring = "ErroringCollection"
+    weaviate_mock.expect_request(f"/v1/schema/{non_existing}").respond_with_json(
+        response_json={"error": [{"message": "collection not found"}]}, status=404
+    )
+    weaviate_mock.expect_request(f"/v1/schema/{erroring}").respond_with_json(
+        response_json={"error": [{"message": "this is an error"}]}, status=500
+    )
+
+    async with weaviate.use_async_with_local(
+        port=MOCK_PORT, host=MOCK_IP, grpc_port=MOCK_PORT_GRPC, skip_init_checks=True
+    ) as client:
+        assert not await client.collections.use(non_existing).exists()
+        with pytest.raises(weaviate.exceptions.UnexpectedStatusCodeError) as e:
+            await client.collections.use(erroring).exists()
+        assert e.value.status_code == 500
+
+
 def test_grpc_client_version_header(
     metadata_capture_collection: tuple[
         weaviate.collections.Collection, MockMetadataCaptureWeaviateService

weaviate/collections/collection/async_.py

@@ -27,6 +27,7 @@
 from weaviate.collections.query import _QueryCollectionAsync
 from weaviate.collections.tenants import _TenantsAsync
 from weaviate.connect.v4 import ConnectionAsync
+from weaviate.exceptions import UnexpectedStatusCodeError
 from weaviate.types import UUID
 
 from .base import _CollectionBase
@@ -183,8 +184,10 @@ async def exists(self) -> bool:
         try:
             await self.config.get(simple=True)
             return True
-        except Exception:
-            return False
+        except UnexpectedStatusCodeError as e:
+            if e.status_code == 404:
+                return False
+            raise e
 
     async def shards(self) -> List[Shard]:
         """Get the statuses of all the shards of this collection.