[Perf][CI] Reuse the Whisper judge worker across a test module (#6208)

Signed-off-by: Shenglei Fu <sfu@confluent.io>
Co-authored-by: Hongsheng Liu <liuhongsheng4@huawei.com>

tests/helpers/tests/test_runtime_transcriber_release.py

@@ -0,0 +1,74 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+"""The server/runner fixtures free the Whisper judge around each instance.
+
+iter_omni_server and iter_omni_runner both wrap their body in the same
+_whisper_device_free_around() context manager, so one representative path
+exercises its enter/exit and exception behavior.
+"""
+
+import threading
+from types import SimpleNamespace
+
+import pytest
+
+from tests.helpers import runtime
+from tests.helpers.runtime import OmniServerParams
+
+pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
+
+
+@pytest.fixture
+def events(monkeypatch) -> list[str]:
+    """Record construction and release in order."""
+    calls: list[str] = []
+
+    class FakeServer:
+        def __init__(self, *args, **kwargs):
+            calls.append("construct")
+
+        def __enter__(self):
+            return self
+
+        def __exit__(self, *exc):
+            return False
+
+    monkeypatch.setattr(runtime, "OmniServer", FakeServer)
+    monkeypatch.setattr(runtime, "release_audio_transcriber", lambda: calls.append("release"))
+    monkeypatch.setattr(
+        "tests.helpers.stage_config.stage_config_path_for_run_level",
+        lambda path, run_level: None,
+    )
+    return calls
+
+
+def _server_generator():
+    request = SimpleNamespace(
+        param=OmniServerParams(model="fake-model"),
+        node=SimpleNamespace(get_closest_marker=lambda name: None),
+    )
+    return runtime.iter_omni_server(request, "core_model", "", threading.Lock())
+
+
+def test_releases_before_construction_and_after_teardown(events):
+    generator = _server_generator()
+    generator.send(None)
+
+    assert events == ["release", "construct"], "the device must be clear before the model loads"
+
+    with pytest.raises(StopIteration):
+        generator.send(None)
+
+    assert events == ["release", "construct", "release"]
+
+
+def test_failing_test_still_releases(events):
+    """A test that raises must not strand Whisper on the device."""
+    generator = _server_generator()
+    generator.send(None)
+
+    with pytest.raises(RuntimeError, match="assertion blew up"):
+        generator.throw(RuntimeError("assertion blew up"))
+
+    assert events[-1] == "release"