FakeChain Class — langchain Architecture

Architecture documentation for the FakeChain class in test_base.py from the langchain codebase.

Class python

Entity Profile

Dependency Diagram

graph TD
  3765bfcc_b5a9_3ceb_55b5_8f5ca217f561["FakeChain"]
  f3cef70e_11b0_61c9_7ec0_7308f4b45056["Chain"]
  3765bfcc_b5a9_3ceb_55b5_8f5ca217f561 -->|extends| f3cef70e_11b0_61c9_7ec0_7308f4b45056
  cbc5b920_9825_eac5_8cc4_bc8187fb214c["test_base.py"]
  3765bfcc_b5a9_3ceb_55b5_8f5ca217f561 -->|defined in| cbc5b920_9825_eac5_8cc4_bc8187fb214c
  9028ab6b_0fa9_940c_98c3_536a7e2d2285["input_keys()"]
  3765bfcc_b5a9_3ceb_55b5_8f5ca217f561 -->|method| 9028ab6b_0fa9_940c_98c3_536a7e2d2285
  09b39aa3_226f_77f0_54dc_0868122884af["output_keys()"]
  3765bfcc_b5a9_3ceb_55b5_8f5ca217f561 -->|method| 09b39aa3_226f_77f0_54dc_0868122884af
  facc7f34_6e73_d7f9_19ad_3b7e6a4c6d3f["_call()"]
  3765bfcc_b5a9_3ceb_55b5_8f5ca217f561 -->|method| facc7f34_6e73_d7f9_19ad_3b7e6a4c6d3f

Relationship Graph

Source Code

libs/langchain/tests/unit_tests/chains/test_base.py lines 41–66

class FakeChain(Chain):
    """Fake chain class for testing purposes."""

    be_correct: bool = True
    the_input_keys: list[str] = ["foo"]
    the_output_keys: list[str] = ["bar"]

    @property
    def input_keys(self) -> list[str]:
        """Input keys."""
        return self.the_input_keys

    @property
    def output_keys(self) -> list[str]:
        """Output key of bar."""
        return self.the_output_keys

    @override
    def _call(
        self,
        inputs: dict[str, str],
        run_manager: CallbackManagerForChainRun | None = None,
    ) -> dict[str, str]:
        if self.be_correct:
            return {"bar": "baz"}
        return {"baz": "bar"}