[Test] Remove VLLM_USE_V1 in example and tests (#1733)

V1 is enabled by default, no need to set it by hand now. This PR remove
the useless setting in example and tests

- vLLM version: v0.9.2
- vLLM main:
9ad0a4588b

Signed-off-by: wangxiyuan <wangxiyuan1007@gmail.com>

tests/e2e/utils.py

@@ -0,0 +1,106 @@
+#
+# Copyright (c) 2025 Huawei Technologies Co., Ltd. All Rights Reserved.
+# This file is a part of the vllm-ascend project.
+# Adapted from vllm-project/vllm/tests/utils.py
+# 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.
+#
+
+import functools
+import os
+import signal
+from collections.abc import Sequence
+from typing import Callable
+
+import torch
+import torch.nn.functional as F
+from typing_extensions import ParamSpec
+
+_P = ParamSpec("_P")
+
+
+def fork_new_process_for_each_test(
+        f: Callable[_P, None]) -> Callable[_P, None]:
+    """Decorator to fork a new process for each test function.
+    See https://github.com/vllm-project/vllm/issues/7053 for more details.
+    """
+
+    @functools.wraps(f)
+    def wrapper(*args: _P.args, **kwargs: _P.kwargs) -> None:
+        # Make the process the leader of its own process group
+        # to avoid sending SIGTERM to the parent process
+        os.setpgrp()
+        from _pytest.outcomes import Skipped
+        pid = os.fork()
+        print(f"Fork a new process to run a test {pid}")
+        if pid == 0:
+            try:
+                f(*args, **kwargs)
+            except Skipped as e:
+                # convert Skipped to exit code 0
+                print(str(e))
+                os._exit(0)
+            except Exception:
+                import traceback
+                traceback.print_exc()
+                os._exit(1)
+            else:
+                os._exit(0)
+        else:
+            pgid = os.getpgid(pid)
+            _pid, _exitcode = os.waitpid(pid, 0)
+            # ignore SIGTERM signal itself
+            old_signal_handler = signal.signal(signal.SIGTERM, signal.SIG_IGN)
+            # kill all child processes
+            os.killpg(pgid, signal.SIGTERM)
+            # restore the signal handler
+            signal.signal(signal.SIGTERM, old_signal_handler)
+            assert _exitcode == 0, (f"function {f} failed when called with"
+                                    f" args {args} and kwargs {kwargs}")
+
+    return wrapper
+
+
+def matryoshka_fy(tensor: torch.Tensor, dimensions: int):
+    tensor = torch.tensor(tensor)
+    tensor = tensor[..., :dimensions]
+    tensor = F.normalize(tensor, p=2, dim=1)
+    return tensor
+
+
+def check_embeddings_close(
+    *,
+    embeddings_0_lst: Sequence[list[float]],
+    embeddings_1_lst: Sequence[list[float]],
+    name_0: str,
+    name_1: str,
+    tol: float = 1e-3,
+) -> None:
+    assert len(embeddings_0_lst) == len(embeddings_1_lst)
+
+    for prompt_idx, (embeddings_0, embeddings_1) in enumerate(
+            zip(embeddings_0_lst, embeddings_1_lst)):
+        assert len(embeddings_0) == len(embeddings_1), (
+            f"Length mismatch: {len(embeddings_0)} vs. {len(embeddings_1)}")
+
+        sim = F.cosine_similarity(torch.tensor(embeddings_0),
+                                  torch.tensor(embeddings_1),
+                                  dim=0)
+
+        fail_msg = (f"Test{prompt_idx}:"
+                    f"\nCosine similarity: \t{sim:.4f}"
+                    f"\n{name_0}:\t{embeddings_0[:16]!r}"
+                    f"\n{name_1}:\t{embeddings_1[:16]!r}")
+
+        assert sim >= 1 - tol, fail_msg