fake_callback_handler.py — langchain Source File

Source Code

"""A fake callback handler for testing purposes."""

from itertools import chain
from typing import Any
from uuid import UUID

from langchain_core.callbacks.base import AsyncCallbackHandler, BaseCallbackHandler
from langchain_core.messages import BaseMessage
from pydantic import BaseModel
from typing_extensions import override


class BaseFakeCallbackHandler(BaseModel):
    """Base fake callback handler for testing."""

    starts: int = 0
    ends: int = 0
    errors: int = 0
    text: int = 0
    ignore_llm_: bool = False
    ignore_chain_: bool = False
    ignore_agent_: bool = False
    ignore_retriever_: bool = False
    ignore_chat_model_: bool = False

    # to allow for similar callback handlers that are not technically equal
    fake_id: str | None = None

    # add finer-grained counters for easier debugging of failing tests
    chain_starts: int = 0
    chain_ends: int = 0
    llm_starts: int = 0
    llm_ends: int = 0
    llm_streams: int = 0
    tool_starts: int = 0
    tool_ends: int = 0
    agent_actions: int = 0
    agent_ends: int = 0
    chat_model_starts: int = 0
    retriever_starts: int = 0
    retriever_ends: int = 0
    retriever_errors: int = 0
    retries: int = 0


class BaseFakeCallbackHandlerMixin(BaseFakeCallbackHandler):
    """Base fake callback handler mixin for testing."""

    def on_llm_start_common(self) -> None:
        self.llm_starts += 1
        self.starts += 1

    def on_llm_end_common(self) -> None:
        self.llm_ends += 1
        self.ends += 1

    def on_llm_error_common(self) -> None:
        self.errors += 1

    def on_llm_new_token_common(self) -> None:
// ... (366 more lines)