fix(collections): correct logic in exists() method

- fix existing condition in `Collections.exists()` method
- add tests to verify collection existence checking
- ensure proper return when collection is in cache

Author: tharropoulos

src/typesense/collections.py

@@ -61,17 +61,28 @@ def __contains__(self, collection_name: str) -> bool:
         """
         Check if a collection exists in Typesense.
 
+        This method tries to retrieve the specified collection to check for its existence,
+        utilizing the Collection.retrieve() method but without caching non-existent collections.
+
         Args:
             collection_name (str): The name of the collection to check.
 
         Returns:
             bool: True if the collection exists, False otherwise.
         """
+        if collection_name in self.collections:
+            try:
+                self.collections[collection_name].retrieve()
+                return True
+            except Exception:
+                self.collections.pop(collection_name, None)
+                return False
+        
         try:
-            all_collections = self.retrieve()
+            Collection(self.api_call, collection_name).retrieve()
+            return True
         except Exception:
             return False
-        return any(coll["name"] == collection_name for coll in all_collections)
 
     def __getitem__(self, collection_name: str) -> Collection[TDoc]:
         """

tests/collections_test.py

@@ -293,3 +293,16 @@ def test_actual_retrieve(
 
     response[0].pop("created_at")
     assert response == expected
+
+
+def test_actual_contains(
+    actual_collections: Collections,
+    delete_all: None,
+    create_collection: None,
+) -> None:
+    """Test that the Collections object can check if a collection exists in Typesense."""
+    # Test for existing collection
+    assert "companies" in actual_collections
+
+    # Test for non-existing collection
+    assert "non_existent_collection" not in actual_collections