FakeModel Class — langchain Architecture

Source Code

libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_tool_emulator.py lines 42–82

class FakeModel(GenericFakeChatModel):
    """Fake model that supports bind_tools."""

    tool_style: Literal["openai", "anthropic"] = "openai"

    def bind_tools(
        self,
        tools: Sequence[dict[str, Any] | type[BaseModel] | Callable[..., Any] | BaseTool],
        **_kwargs: Any,
    ) -> Runnable[LanguageModelInput, AIMessage]:
        if len(tools) == 0:
            msg = "Must provide at least one tool"
            raise ValueError(msg)

        tool_dicts = []
        for tool_ in tools:
            if isinstance(tool_, dict):
                tool_dicts.append(tool_)
                continue
            if not isinstance(tool_, BaseTool):
                msg = "Only BaseTool and dict is supported by FakeModel.bind_tools"
                raise TypeError(msg)

            # NOTE: this is a simplified tool spec for testing purposes only
            if self.tool_style == "openai":
                tool_dicts.append(
                    {
                        "type": "function",
                        "function": {
                            "name": tool_.name,
                        },
                    }
                )
            elif self.tool_style == "anthropic":
                tool_dicts.append(
                    {
                        "name": tool_.name,
                    }
                )

        return self.bind(tools=tool_dicts)