[Misc] Improve conftest (vllm-project#5681)

Author: DarkLight1337

tests/conftest.py

@@ -365,7 +365,7 @@ def __exit__(self, exc_type, exc_value, traceback):
         cleanup()
 
 
-@pytest.fixture
+@pytest.fixture(scope="session")
 def hf_runner():
     return HfRunner
 
@@ -385,6 +385,7 @@ def __init__(
         block_size: int = 16,
         enable_chunked_prefill: bool = False,
         swap_space: int = 4,
+        enforce_eager: bool = False,
         **kwargs,
     ) -> None:
         self.model = LLM(
@@ -393,6 +394,7 @@ def __init__(
             trust_remote_code=True,
             dtype=dtype,
             swap_space=swap_space,
+            enforce_eager=enforce_eager,
             disable_log_stats=disable_log_stats,
             tensor_parallel_size=tensor_parallel_size,
             max_model_len=max_model_len,