test_reward.py

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project

import weakref

import pytest
import torch

from tests.models.utils import softmax
from vllm import LLM, PoolingParams
from vllm.distributed import cleanup_dist_env_and_memory

MODEL_NAME = "internlm/internlm2-1_8b-reward"

prompts = ["The chef prepared a delicious meal."]


@pytest.fixture(scope="module")
def llm():
    # pytest caches the fixture so we use weakref.proxy to
    # enable garbage collection
    llm = LLM(
        model=MODEL_NAME,
        max_num_batched_tokens=32768,
        tensor_parallel_size=1,
        gpu_memory_utilization=0.75,
        enforce_eager=True,
        trust_remote_code=True,
        seed=0,
    )

    yield weakref.proxy(llm)

    del llm

    cleanup_dist_env_and_memory()


@pytest.mark.skip_global_cleanup
def test_pooling_params(llm: LLM):
    def get_outputs(softmax):
        outputs = llm.reward(
            prompts, pooling_params=PoolingParams(softmax=softmax), use_tqdm=False
        )
        return torch.cat([x.outputs.data for x in outputs])

    default = get_outputs(softmax=None)
    w_softmax = get_outputs(softmax=True)
    wo_softmax = get_outputs(softmax=False)

    assert torch.allclose(default, w_softmax, atol=1e-2), "Default should use softmax."
    assert not torch.allclose(w_softmax, wo_softmax, atol=1e-2), (
        "wo_softmax should not use softmax."
    )
    assert torch.allclose(softmax(wo_softmax), w_softmax, atol=1e-2), (
        "w_softmax should be close to softmax(wo_softmax)."
    )