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TestBasicCommand Class — langchain Architecture

Architecture documentation for the TestBasicCommand class in test_wrap_model_call_state_update.py from the langchain codebase.

Class python

Entity Profile

Dependency Diagram

graph TD
  32ccf275_216c_0c5f_4a10_07f3bc9d69a5["TestBasicCommand"]
  949c7cf4_56fe_f3b4_cd89_9631a7e9cb1e["AgentMiddleware"]
  32ccf275_216c_0c5f_4a10_07f3bc9d69a5 -->|extends| 949c7cf4_56fe_f3b4_cd89_9631a7e9cb1e
  e4070722_d3c6_f73d_d727_5779ab576a2a["AgentState"]
  32ccf275_216c_0c5f_4a10_07f3bc9d69a5 -->|extends| e4070722_d3c6_f73d_d727_5779ab576a2a
  08361e76_a995_1e57_f200_e292474e2f00["test_wrap_model_call_state_update.py"]
  32ccf275_216c_0c5f_4a10_07f3bc9d69a5 -->|defined in| 08361e76_a995_1e57_f200_e292474e2f00
  04483ccb_4c64_7ff1_4669_71171222d0eb["test_command_messages_added_alongside_model_messages()"]
  32ccf275_216c_0c5f_4a10_07f3bc9d69a5 -->|method| 04483ccb_4c64_7ff1_4669_71171222d0eb
  dd6f5635_507b_9aec_47c5_038caeb19080["test_command_with_extra_messages_and_model_response()"]
  32ccf275_216c_0c5f_4a10_07f3bc9d69a5 -->|method| dd6f5635_507b_9aec_47c5_038caeb19080
  b9c9a03c_fc16_a250_4e3b_00804123b967["test_command_structured_response_conflicts_with_model_response()"]
  32ccf275_216c_0c5f_4a10_07f3bc9d69a5 -->|method| b9c9a03c_fc16_a250_4e3b_00804123b967
  e327cf86_4eab_962c_02fa_5a242f4ebbbb["test_command_with_custom_state_field()"]
  32ccf275_216c_0c5f_4a10_07f3bc9d69a5 -->|method| e327cf86_4eab_962c_02fa_5a242f4ebbbb

Relationship Graph

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_wrap_model_call_state_update.py lines 26–142

class TestBasicCommand:
    """Test basic ExtendedModelResponse functionality with Command."""

    def test_command_messages_added_alongside_model_messages(self) -> None:
        """Command messages are added alongside model response messages (additive)."""

        class AddMessagesMiddleware(AgentMiddleware):
            def wrap_model_call(
                self,
                request: ModelRequest,
                handler: Callable[[ModelRequest], ModelResponse],
            ) -> ExtendedModelResponse:
                response = handler(request)
                custom_msg = HumanMessage(content="Custom message", id="custom")
                return ExtendedModelResponse(
                    model_response=response,
                    command=Command(update={"messages": [custom_msg]}),
                )

        model = GenericFakeChatModel(messages=iter([AIMessage(content="Hello!")]))
        agent = create_agent(model=model, middleware=[AddMessagesMiddleware()])

        result = agent.invoke({"messages": [HumanMessage(content="Hi")]})

        # Both model response AND command messages appear (additive via add_messages)
        messages = result["messages"]
        assert len(messages) == 3
        assert messages[0].content == "Hi"
        assert messages[1].content == "Hello!"
        assert messages[2].content == "Custom message"

    def test_command_with_extra_messages_and_model_response(self) -> None:
        """Middleware can add extra messages via command alongside model messages."""

        class ExtraMessagesMiddleware(AgentMiddleware):
            def wrap_model_call(
                self,
                request: ModelRequest,
                handler: Callable[[ModelRequest], ModelResponse],
            ) -> ExtendedModelResponse:
                response = handler(request)
                summary = HumanMessage(content="Summary", id="summary")
                return ExtendedModelResponse(
                    model_response=response,
                    command=Command(update={"messages": [summary]}),
                )

        model = GenericFakeChatModel(messages=iter([AIMessage(content="Hello!")]))
        agent = create_agent(model=model, middleware=[ExtraMessagesMiddleware()])

        result = agent.invoke({"messages": [HumanMessage(content="Hi")]})

        messages = result["messages"]
        assert len(messages) == 3
        assert messages[0].content == "Hi"
        assert messages[1].content == "Hello!"
        assert messages[2].content == "Summary"

    def test_command_structured_response_conflicts_with_model_response(self) -> None:
        """Command and model response both setting structured_response raises."""

        class OverrideMiddleware(AgentMiddleware):
            def wrap_model_call(
                self,
                request: ModelRequest,
                handler: Callable[[ModelRequest], ModelResponse],
            ) -> ExtendedModelResponse:
                response = handler(request)
                response_with_structured = ModelResponse(
                    result=response.result,
                    structured_response={"from": "model"},
                )
                return ExtendedModelResponse(
                    model_response=response_with_structured,
                    command=Command(
                        update={
                            "structured_response": {"from": "command"},
                        }
                    ),
                )

Defined In

Extends

Source

Frequently Asked Questions

What is the TestBasicCommand class?
TestBasicCommand is a class in the langchain codebase, defined in libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_wrap_model_call_state_update.py.
Where is TestBasicCommand defined?
TestBasicCommand is defined in libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_wrap_model_call_state_update.py at line 26.
What does TestBasicCommand extend?
TestBasicCommand extends AgentMiddleware, AgentState.

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