[e2e] add pcp e2e (#5141)

### What this PR does / why we need it?
add pcp accuracy e2e test case

- vLLM version: v0.12.0
- vLLM main:
ad32e3e19c
---------
Signed-off-by: weiguihua2 <weiguihua2@huawei.com>

.github/workflows/_e2e_test.yaml

@@ -268,6 +268,7 @@ jobs:
           pytest -sv --durations=0 tests/e2e/multicard/test_offline_inference_distributed.py::test_models_distributed_Kimi_K2_Thinking_W4A16
           pytest -sv --durations=0 tests/e2e/multicard/test_data_parallel_tp2.py
           pytest -sv --durations=0 tests/e2e/multicard/long_sequence/test_basic.py
+          pytest -sv --durations=0 tests/e2e/multicard/long_sequence/test_accuracy.py
 
       - name: Install Ascend toolkit & triton_ascend (for Qwen3-Next-80B-A3B-Instruct)
         shell: bash -l {0}

tests/e2e/multicard/long_sequence/test_accuracy.py

@@ -0,0 +1,102 @@
+#
+# Copyright (c) 2025 Huawei Technologies Co., Ltd. All Rights Reserved.
+# Copyright 2023 The vLLM team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+"""
+Compare the outputs of vLLM with and without context parallel.
+
+Run `pytest tests/e2e/multicard/long_sequence/test_accuracy.py`.
+"""
+
+import pytest
+
+from tests.e2e.conftest import VllmRunner
+from tests.e2e.model_utils import check_outputs_equal
+from vllm_ascend.utils import vllm_version_is
+
+MODELS = [
+    "Qwen/Qwen3-8B",
+    "vllm-ascend/DeepSeek-V2-Lite-W8A8",
+]
+
+
+@pytest.mark.skipif(vllm_version_is('0.12.0'),
+                    reason="0.12.0 is not supported for context sequence.")
+@pytest.mark.parametrize("model", MODELS)
+@pytest.mark.parametrize("max_tokens", [10])
+def test_output_between_tp_and_cp(
+    model: str,
+    max_tokens: int,
+) -> None:
+    prompts = [
+        "The president of the United States is", "The capital of France is"
+    ]
+
+    common_kwargs = {
+        "max_model_len": 1024,
+    }
+
+    if model == "vllm-ascend/DeepSeek-V2-Lite-W8A8":
+        cp_kwargs = {
+            "tensor_parallel_size": 2,
+            "decode_context_parallel_size": 2,
+            "prefill_context_parallel_size": 2,
+            "enable_expert_parallel": True,
+            "enforce_eager": True,
+            "quantization": "ascend",
+        }
+        tp_kwargs = {
+            "tensor_parallel_size": 4,
+            "enable_expert_parallel": True,
+            "enforce_eager": True,
+            "quantization": "ascend",
+        }
+
+    else:
+        cp_kwargs = {
+            "tensor_parallel_size": 1,
+            "decode_context_parallel_size": 1,
+            "prefill_context_parallel_size": 2,
+            "enforce_eager": False,
+            "compilation_config": {
+                "cudagraph_mode": "FULL_DECODE_ONLY",
+                "cudagraph_capture_sizes": [4, 8, 24, 48, 60]
+            },
+        }
+        tp_kwargs = {
+            "tensor_parallel_size": 2,
+            "enforce_eager": True,
+        }
+
+    cp_full_kwargs = {}
+    cp_full_kwargs.update(common_kwargs)
+    cp_full_kwargs.update(cp_kwargs)
+
+    tp_full_kwargs = {}
+    tp_full_kwargs.update(common_kwargs)
+    tp_full_kwargs.update(tp_kwargs)
+    with VllmRunner(model, **cp_full_kwargs) as runner:
+        vllm_context_parallel_outputs = runner.generate_greedy(
+            prompts, max_tokens)
+
+    with VllmRunner(model, **tp_full_kwargs) as runner:
+        vllm_eager_outputs = runner.generate_greedy(prompts, max_tokens)
+
+    check_outputs_equal(
+        outputs_0_lst=vllm_eager_outputs,
+        outputs_1_lst=vllm_context_parallel_outputs,
+        name_0="vllm_eager_outputs",
+        name_1="vllm_context_parallel_outputs",
+    )