[CI/Build] Reuse code for checking output consistency (#5988)

tests/basic_correctness/test_preemption.py

@@ -12,6 +12,8 @@ from vllm import SamplingParams
 from vllm.core.scheduler import (ARTIFICIAL_PREEMPTION_MAX_CNT,
                                  ENABLE_ARTIFICIAL_PREEMPT)
 
+from ..models.utils import check_outputs_equal
+
 MODELS = [
     "facebook/opt-125m",
 ]
@@ -94,13 +96,13 @@ def test_preemption(
         total_preemption = (
             vllm_model.model.llm_engine.scheduler.num_cumulative_preemption)
 
-    for i in range(len(example_prompts)):
-        hf_output_ids, hf_output_str = hf_outputs[i]
-        vllm_output_ids, vllm_output_str = vllm_outputs[i]
-        assert hf_output_str == vllm_output_str, (
-            f"Test{i}:\nHF: {hf_output_str!r}\nvLLM: {vllm_output_str!r}")
-        assert hf_output_ids == vllm_output_ids, (
-            f"Test{i}:\nHF: {hf_output_ids}\nvLLM: {vllm_output_ids}")
+    check_outputs_equal(
+        outputs_0_lst=hf_outputs,
+        outputs_1_lst=vllm_outputs,
+        name_0="hf",
+        name_1="vllm",
+    )
+
     assert ("is preempted by PreemptionMode.RECOMPUTE mode because there "
             "is not enough KV cache space." in caplog_vllm.text)
     # Ensure the count bucket of request-level histogram metrics matches