adding more tests

haystack_experimental/components/retrievers/auto_merging_retriever.py

@@ -132,14 +132,13 @@ def try_merge_level(documents: List[Document]) -> List[Document]:
                 return []
 
             docs_to_return = []
-            # group the documents by their parent documents
-            parent_documents: Dict[str, List[Document]] = defaultdict(list)
+            parent_documents: Dict[str, List[Document]] = defaultdict(list)  # to group the documents by their parent
 
             for doc in documents:
-                if doc.meta.get("__parent_id"):  # Only group docs that have parents
+                if doc.meta.get("__parent_id"):  # only docs that have parents
                     parent_documents[doc.meta["__parent_id"]].append(doc)
                 else:
-                    docs_to_return.append(doc)  # Keep docs that have no parents
+                    docs_to_return.append(doc)  # keep docs that have no parents
 
             # If no documents have parents, we're done
             if not parent_documents:

test/components/retrievers/test_auto_merging_retriever.py

@@ -85,6 +85,10 @@ def test_run_mixed_valid_and_invalid_documents(self):
         with pytest.raises(ValueError, match="The matched leaf documents do not have the required meta field '__parent_id'"):
             retriever.run(matched_leaf_documents=docs)
 
+    def test_run_empty_documents(self):
+        retriever = AutoMergingRetriever(InMemoryDocumentStore())
+        assert retriever.run([]) == {"documents": []}
+
     def test_to_dict(self):
         retriever = AutoMergingRetriever(InMemoryDocumentStore(), threshold=0.7)
         expected = retriever.to_dict()