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

tests/rerankers/conftest.py

@@ -1,3 +1,5 @@
+import sys
+from types import ModuleType
 from unittest.mock import MagicMock, patch
 
 import pytest
@@ -9,3 +11,33 @@ def mock_llm():
         mock_llm_instance = MagicMock()
         mock_factory.create.return_value = mock_llm_instance
         yield mock_factory, mock_llm_instance
+
+
+@pytest.fixture
+def mock_cohere(monkeypatch):
+    """Provide a fake ``cohere`` module so CohereReranker imports/constructs."""
+    fake_cohere = ModuleType("cohere")
+    fake_client = MagicMock()
+    fake_cohere.Client = MagicMock(return_value=fake_client)
+    monkeypatch.setitem(sys.modules, "cohere", fake_cohere)
+
+    import mem0.reranker.cohere_reranker as cohere_reranker
+
+    monkeypatch.setattr(cohere_reranker, "cohere", fake_cohere, raising=False)
+    monkeypatch.setattr(cohere_reranker, "COHERE_AVAILABLE", True, raising=False)
+    return cohere_reranker, fake_client
+
+
+@pytest.fixture
+def mock_zero_entropy(monkeypatch):
+    """Provide a fake ``zeroentropy`` module so ZeroEntropyReranker imports."""
+    fake_module = ModuleType("zeroentropy")
+    fake_client = MagicMock()
+    fake_module.ZeroEntropy = MagicMock(return_value=fake_client)
+    monkeypatch.setitem(sys.modules, "zeroentropy", fake_module)
+
+    import mem0.reranker.zero_entropy_reranker as zero_entropy_reranker
+
+    monkeypatch.setattr(zero_entropy_reranker, "ZeroEntropy", fake_module.ZeroEntropy, raising=False)
+    monkeypatch.setattr(zero_entropy_reranker, "ZERO_ENTROPY_AVAILABLE", True, raising=False)
+    return zero_entropy_reranker, fake_client