fix: OSS Python SDK hygiene batch, 9 small bug fixes (#6770)

tests/rerankers/test_reranker_fallback_no_mutation.py

@@ -0,0 +1,75 @@
+"""Regression tests pinning that the reranker fallback path never mutates caller-owned documents."""
+
+from unittest.mock import MagicMock, patch
+
+from mem0.configs.rerankers.cohere import CohereRerankerConfig
+from mem0.configs.rerankers.huggingface import HuggingFaceRerankerConfig
+from mem0.configs.rerankers.sentence_transformer import (
+    SentenceTransformerRerankerConfig,
+)
+from mem0.configs.rerankers.zero_entropy import ZeroEntropyRerankerConfig
+from mem0.reranker.huggingface_reranker import HuggingFaceReranker
+from mem0.reranker.sentence_transformer_reranker import SentenceTransformerReranker
+
+
+def _docs(n):
+    return [{"memory": f"doc{i}"} for i in range(n)]
+
+
+class TestCohereFallbackNoMutation:
+    def test_fallback_does_not_mutate_original_documents(self, mock_cohere):
+        module, fake_client = mock_cohere
+        fake_client.rerank.side_effect = RuntimeError("API error")
+
+        reranker = module.CohereReranker(CohereRerankerConfig(api_key="test-key"))
+        documents = _docs(3)
+        result = reranker.rerank("query", documents)
+
+        assert all("rerank_score" not in doc for doc in documents)
+        assert all(doc["rerank_score"] == 0.0 for doc in result)
+
+
+class TestZeroEntropyFallbackNoMutation:
+    def test_fallback_does_not_mutate_original_documents(self, mock_zero_entropy):
+        module, fake_client = mock_zero_entropy
+        fake_client.models.rerank.side_effect = RuntimeError("API error")
+
+        reranker = module.ZeroEntropyReranker(ZeroEntropyRerankerConfig(api_key="test-key"))
+        documents = _docs(3)
+        result = reranker.rerank("query", documents)
+
+        assert all("rerank_score" not in doc for doc in documents)
+        assert all(doc["rerank_score"] == 0.0 for doc in result)
+
+
+class TestHuggingFaceFallbackNoMutation:
+    def test_fallback_does_not_mutate_original_documents(self):
+        with (
+            patch("mem0.reranker.huggingface_reranker.AutoTokenizer") as mock_tokenizer_cls,
+            patch("mem0.reranker.huggingface_reranker.AutoModelForSequenceClassification") as mock_model_cls,
+        ):
+            mock_tokenizer = MagicMock(side_effect=RuntimeError("tokenizer error"))
+            mock_tokenizer_cls.from_pretrained.return_value = mock_tokenizer
+            mock_model_cls.from_pretrained.return_value = MagicMock()
+
+            reranker = HuggingFaceReranker(HuggingFaceRerankerConfig())
+            documents = _docs(3)
+            result = reranker.rerank("query", documents)
+
+        assert all("rerank_score" not in doc for doc in documents)
+        assert all(doc["rerank_score"] == 0.0 for doc in result)
+
+
+class TestSentenceTransformerFallbackNoMutation:
+    def test_fallback_does_not_mutate_original_documents(self):
+        with patch("mem0.reranker.sentence_transformer_reranker.CrossEncoder") as mock_cross_encoder_cls:
+            mock_model = MagicMock()
+            mock_model.predict.side_effect = RuntimeError("predict error")
+            mock_cross_encoder_cls.return_value = mock_model
+
+            reranker = SentenceTransformerReranker(SentenceTransformerRerankerConfig())
+            documents = _docs(3)
+            result = reranker.rerank("query", documents)
+
+        assert all("rerank_score" not in doc for doc in documents)
+        assert all(doc["rerank_score"] == 0.0 for doc in result)