test_apply_to_tool_results() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_pii.py lines 423–448

    def test_apply_to_tool_results(self) -> None:
        """Test that middleware processes tool results when enabled."""
        middleware = PIIMiddleware(
            "email", strategy="redact", apply_to_input=False, apply_to_tool_results=True
        )

        # Simulate a conversation with tool call and result containing PII
        state = AgentState[Any](
            messages=[
                HumanMessage("Search for John"),
                AIMessage(
                    content="",
                    tool_calls=[ToolCall(name="search", args={}, id="call_123", type="tool_call")],
                ),
                ToolMessage(content="Found: john@example.com", tool_call_id="call_123"),
            ]
        )

        result = middleware.before_model(state, Runtime())

        assert result is not None
        # Check that the tool message was redacted
        tool_msg = result["messages"][2]
        assert isinstance(tool_msg, ToolMessage)
        assert "[REDACTED_EMAIL]" in tool_msg.content
        assert "john@example.com" not in tool_msg.content