[Bugfix][MiniCPM-o] Fix duplex camera frame fixture (#6757)

Signed-off-by: psv666 <2693925048@qq.com>

tests/e2e/online_serving/helpers/minicpmo_4_5_duplex.py

@@ -101,7 +101,8 @@ def duplex_camera_frames(*, seconds: int, cache_dir: Path) -> list[str]:
     from tests.helpers.media import generate_synthetic_video
 
     video = generate_synthetic_video(448, 448, 30 * seconds, cache_dir=cache_dir)
-    return _video_frames_from_file(Path(video["file_path"]))
+    frames, _ = _video_frames_from_file(Path(video["file_path"]))
+    return frames
 
 
 def realtime_url(omni_server) -> str:

tests/e2e/online_serving/test_minicpmo_realtime_duplex_drivers.py

@@ -1926,6 +1926,28 @@ def test_realtime_duplex_demo_sends_each_units_stacked_composite_next_to_its_bas
     assert _sent_video_frames(messages) == [["f0", "s0"], ["f1", "s1"], ["f2"]]
 
 
+def test_minicpmo_duplex_camera_fixture_returns_flat_base_frame_track(tmp_path, monkeypatch):
+    from tests.e2e.online_serving.helpers import minicpmo_4_5_duplex as fixtures
+    from tests.e2e.online_serving.helpers import minicpmo_realtime_duplex_scenarios as demo
+    from tests.helpers import media
+
+    video_path = tmp_path / "camera.mp4"
+    monkeypatch.setattr(
+        media,
+        "generate_synthetic_video",
+        lambda *args, **kwargs: {"file_path": str(video_path)},
+    )
+    monkeypatch.setattr(
+        demo,
+        "_video_frames_from_file",
+        lambda path: (["frame-0", "frame-1"], [None, None]),
+    )
+
+    frames = fixtures.duplex_camera_frames(seconds=2, cache_dir=tmp_path)
+
+    assert frames == ["frame-0", "frame-1"]
+
+
 def test_realtime_duplex_demo_decodes_a_video_file_into_one_frame_per_second(tmp_path):
     pytest.importorskip("cv2")
     pytest.importorskip("imageio")