langchain/libs/community/tests/unit_tests/agents/test_react.py

"""Unit tests for ReAct."""

from typing import Union

from langchain.agents.react.base import ReActChain, ReActDocstoreAgent
from langchain_core.agents import AgentAction
from langchain_core.documents import Document
from langchain_core.language_models import FakeListLLM
from langchain_core.prompts.prompt import PromptTemplate
from langchain_core.tools import Tool

from langchain_community.docstore.base import Docstore

_PAGE_CONTENT = """This is a page about LangChain.

It is a really cool framework.

What isn't there to love about langchain?

Made in 2022."""

_FAKE_PROMPT = PromptTemplate(input_variables=["input"], template="{input}")


class FakeDocstore(Docstore):
    """Fake docstore for testing purposes."""

    def search(self, search: str) -> Union[str, Document]:
        """Return the fake document."""
        document = Document(page_content=_PAGE_CONTENT)
        return document


def test_predict_until_observation_normal() -> None:
    """Test predict_until_observation when observation is made normally."""
    outputs = ["foo\nAction: Search[foo]"]
    fake_llm = FakeListLLM(responses=outputs)
    tools = [
        Tool(name="Search", func=lambda x: x, description="foo"),
        Tool(name="Lookup", func=lambda x: x, description="bar"),
    ]
    agent = ReActDocstoreAgent.from_llm_and_tools(fake_llm, tools)
    output = agent.plan([], input="")
    expected_output = AgentAction("Search", "foo", outputs[0])
    assert output == expected_output


def test_react_chain() -> None:
    """Test react chain."""
    responses = [
        "I should probably search\nAction: Search[langchain]",
        "I should probably lookup\nAction: Lookup[made]",
        "Ah okay now I know the answer\nAction: Finish[2022]",
    ]
    fake_llm = FakeListLLM(responses=responses)
    react_chain = ReActChain(llm=fake_llm, docstore=FakeDocstore())
    output = react_chain.run("when was langchain made")
    assert output == "2022"


def test_react_chain_bad_action() -> None:
    """Test react chain when bad action given."""
    bad_action_name = "BadAction"
    responses = [
        f"I'm turning evil\nAction: {bad_action_name}[langchain]",
        "Oh well\nAction: Finish[curses foiled again]",
    ]
    fake_llm = FakeListLLM(responses=responses)
    react_chain = ReActChain(llm=fake_llm, docstore=FakeDocstore())
    output = react_chain.run("when was langchain made")
    assert output == "curses foiled again"