langchain/tests/unit_tests/chains/test_base.py

"""Test logic on base chain class."""
from typing import Any, Dict, List, Optional

import pytest
from pydantic import BaseModel

from langchain.callbacks.base import CallbackManager
from langchain.chains.base import Chain
from langchain.schema import BaseMemory
from tests.unit_tests.callbacks.fake_callback_handler import FakeCallbackHandler


class FakeMemory(BaseMemory, BaseModel):
    """Fake memory class for testing purposes."""

    @property
    def memory_variables(self) -> List[str]:
        """Return baz variable."""
        return ["baz"]

    def load_memory_variables(
        self, inputs: Optional[Dict[str, Any]] = None
    ) -> Dict[str, str]:
        """Return baz variable."""
        return {"baz": "foo"}

    def save_context(self, inputs: Dict[str, Any], outputs: Dict[str, str]) -> None:
        """Pass."""
        pass

    def clear(self) -> None:
        """Pass."""
        pass


class FakeChain(Chain, BaseModel):
    """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

    def _call(self, inputs: Dict[str, str]) -> Dict[str, str]:
        if self.be_correct:
            return {"bar": "baz"}
        else:
            return {"baz": "bar"}


def test_bad_inputs() -> None:
    """Test errors are raised if input keys are not found."""
    chain = FakeChain()
    with pytest.raises(ValueError):
        chain({"foobar": "baz"})


def test_bad_outputs() -> None:
    """Test errors are raised if outputs keys are not found."""
    chain = FakeChain(be_correct=False)
    with pytest.raises(ValueError):
        chain({"foo": "baz"})


def test_correct_call() -> None:
    """Test correct call of fake chain."""
    chain = FakeChain()
    output = chain({"foo": "bar"})
    assert output == {"foo": "bar", "bar": "baz"}


def test_single_input_correct() -> None:
    """Test passing single input works."""
    chain = FakeChain()
    output = chain("bar")
    assert output == {"foo": "bar", "bar": "baz"}


def test_single_input_error() -> None:
    """Test passing single input errors as expected."""
    chain = FakeChain(the_input_keys=["foo", "bar"])
    with pytest.raises(ValueError):
        chain("bar")


def test_run_single_arg() -> None:
    """Test run method with single arg."""
    chain = FakeChain()
    output = chain.run("bar")
    assert output == "baz"


def test_run_multiple_args_error() -> None:
    """Test run method with multiple args errors as expected."""
    chain = FakeChain()
    with pytest.raises(ValueError):
        chain.run("bar", "foo")


def test_run_kwargs() -> None:
    """Test run method with kwargs."""
    chain = FakeChain(the_input_keys=["foo", "bar"])
    output = chain.run(foo="bar", bar="foo")
    assert output == "baz"


def test_run_kwargs_error() -> None:
    """Test run method with kwargs errors as expected."""
    chain = FakeChain(the_input_keys=["foo", "bar"])
    with pytest.raises(ValueError):
        chain.run(foo="bar", baz="foo")


def test_run_args_and_kwargs_error() -> None:
    """Test run method with args and kwargs."""
    chain = FakeChain(the_input_keys=["foo", "bar"])
    with pytest.raises(ValueError):
        chain.run("bar", foo="bar")


def test_multiple_output_keys_error() -> None:
    """Test run with multiple output keys errors as expected."""
    chain = FakeChain(the_output_keys=["foo", "bar"])
    with pytest.raises(ValueError):
        chain.run("bar")


def test_run_arg_with_memory() -> None:
    """Test run method works when arg is passed."""
    chain = FakeChain(the_input_keys=["foo", "baz"], memory=FakeMemory())
    chain.run("bar")


def test_run_with_callback() -> None:
    """Test run method works when callback manager is passed."""
    handler = FakeCallbackHandler()
    chain = FakeChain(
        callback_manager=CallbackManager(handlers=[handler]), verbose=True
    )
    output = chain.run("bar")
    assert output == "baz"
    assert handler.starts == 1
    assert handler.ends == 1
    assert handler.errors == 0


def test_run_with_callback_not_verbose() -> None:
    """Test run method works when callback manager is passed and not verbose."""
    import langchain

    langchain.verbose = False

    handler = FakeCallbackHandler()
    chain = FakeChain(callback_manager=CallbackManager(handlers=[handler]))
    output = chain.run("bar")
    assert output == "baz"
    assert handler.starts == 0
    assert handler.ends == 0
    assert handler.errors == 0