Add integration test for storage mode switch

tests/integration/test_storage_modes.py

@@ -0,0 +1,10 @@
+import pytest
+from gqlalchemy.exceptions import GQLAlchemyDatabaseError
+from gqlalchemy import create
+
+
+def test_switch_to_on_disk(memgraph):
+    create().node(labels="Person", name="Leslie").execute()
+
+    with pytest.raises(GQLAlchemyDatabaseError):
+        memgraph.set_storage_mode("ON_DISK_TRANSACTIONAL")