test_override_single_attribute() — langchain Function Reference

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_overrides.py lines 24–46

    def test_override_single_attribute(self) -> None:
        """Test overriding a single attribute."""
        model = GenericFakeChatModel(messages=iter([AIMessage(content="Hello")]))
        original_request = ModelRequest(
            model=model,
            system_message=SystemMessage("Original prompt"),
            messages=[HumanMessage("Hi")],
            tool_choice=None,
            tools=[],
            response_format=None,
            state=AgentState(messages=[]),
            runtime=None,
        )

        new_request = original_request.override(system_message=SystemMessage("New prompt"))

        # New request should have the overridden value
        assert new_request.system_prompt == "New prompt"
        # Original request should be unchanged (immutability)
        assert original_request.system_prompt == "Original prompt"
        # Other attributes should be the same
        assert new_request.model == original_request.model
        assert new_request.messages == original_request.messages