fixed impl

metadata-ingestion/src/datahub/testing/compare_metadata_json.py

@@ -84,13 +84,13 @@ def assert_metadata_files_equal(
 
     diff = diff_metadata_json(output, golden, ignore_paths, ignore_order=ignore_order)
     if diff and update_golden:
-        if isinstance(diff, MCPDiff):
-            if diff.apply_delta(golden):
-                write_metadata_file(pathlib.Path(golden_path), golden)
-                return
-
-        # Fallback: just overwrite the golden file
-        shutil.copyfile(str(output_path), str(golden_path))
+        if isinstance(diff, MCPDiff) and diff.is_delta_valid:
+            diff.apply_delta(golden)
+            write_metadata_file(pathlib.Path(golden_path), golden)
+        else:
+            # Fallback: just overwrite the golden file
+            logger.info("Overwriting golden file!!!")
+            shutil.copyfile(str(output_path), str(golden_path))
         return
 
     if diff:

metadata-ingestion/src/datahub/testing/mcp_diff.py

@@ -149,6 +149,7 @@ class MCPDiff:
     aspect_changes: Dict[str, Dict[str, MCPAspectDiff]]  # urn -> aspect -> diff
     urns_added: Set[str]
     urns_removed: Set[str]
+    is_delta_valid: bool
 
     def __bool__(self) -> bool:
         return bool(self.aspect_changes)
@@ -162,25 +163,31 @@ def create(
     ) -> "MCPDiff":
         ignore_paths = [cls.convert_path(path) for path in ignore_paths]
 
+        is_delta_valid = True
         aspect_changes: Dict[str, Dict[str, MCPAspectDiff]] = defaultdict(dict)
         for urn in golden.keys() | output.keys():
             golden_map = golden.get(urn, {})
             output_map = output.get(urn, {})
             for aspect_name in golden_map.keys() | output_map.keys():
+                t1 = golden_map.get(aspect_name, [])
+                t2 = output_map.get(aspect_name, [])
                 diff = DeepDiff(
-                    t1=golden_map.get(aspect_name, []),
-                    t2=output_map.get(aspect_name, []),
+                    t1=t1,
+                    t2=t2,
                     exclude_regex_paths=ignore_paths,
                     ignore_order=True,
                     custom_operators=[DeltaInfoOperator()],
                 )
                 if diff:
                     aspect_changes[urn][aspect_name] = MCPAspectDiff.create(diff)
+                if len(t1) > 1 and len(t2) > 1:
+                    is_delta_valid = False
 
         return cls(
             urns_added=output.keys() - golden.keys(),
             urns_removed=golden.keys() - output.keys(),
             aspect_changes=aspect_changes,
+            is_delta_valid=is_delta_valid,
         )
 
     @staticmethod
@@ -192,17 +199,13 @@ def convert_path(path: str) -> str:
             path,
         )
 
-    def apply_delta(self, golden: List[Dict[str, Any]]) -> bool:
+    def apply_delta(self, golden: List[Dict[str, Any]]) -> None:
         """Update a golden file to match an output file based on the diff.
 
         :param golden: Golden file represented as a list of MCPs, altered in-place.
-        :return: Whether the delta was successfully applied. If false, fallback to copying file when updating golden.
         """
         aspect_diffs = [v for d in self.aspect_changes.values() for v in d.values()]
         for aspect_diff in aspect_diffs:
-            if len(aspect_diff.aspects_changed) > 1:
-                return False
-
             for (_, old, new) in aspect_diff.aspects_changed.keys():
                 golden[old.delta_info.idx] = new.delta_info.original