test(BA-5119): add enum sync guard for ContainerRegistryTypeGQL

Ensures ContainerRegistryTypeGQL stays in sync with the internal
ContainerRegistryType enum to catch drift early.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: fregataa

tests/unit/manager/api/gql/test_container_registry_type_sync.py

@@ -0,0 +1,26 @@
+"""Sync guard: ContainerRegistryTypeGQL must cover all ContainerRegistryType members.
+
+Prevents enum drift between the internal ContainerRegistryType and its GraphQL
+mirror from silently reaching production as a runtime ValueError.
+"""
+
+from __future__ import annotations
+
+from ai.backend.common.container_registry import ContainerRegistryType
+from ai.backend.manager.api.gql.container_registry.types import ContainerRegistryTypeGQL
+
+
+class TestContainerRegistryTypeEnumSync:
+    def test_gql_enum_covers_all_internal_members(self) -> None:
+        internal_values = {member.value for member in ContainerRegistryType}
+        gql_values = {member.value for member in ContainerRegistryTypeGQL}
+        missing = internal_values - gql_values
+        assert not missing, (
+            f"ContainerRegistryTypeGQL is missing members present in ContainerRegistryType: {missing}. "
+            f"Add them to ContainerRegistryTypeGQL to keep the enums in sync."
+        )
+
+    def test_from_enum_roundtrip_for_all_members(self) -> None:
+        for member in ContainerRegistryType:
+            gql_member = ContainerRegistryTypeGQL.from_enum(member)
+            assert gql_member.value == member.value