[output] Add decorator failure regression test

Author: MuhammadBilalKhan267

scenedetect/output/__init__.py

@@ -152,6 +152,7 @@ def write_scene_list(
     Raises:
         TypeError: "delimiter" must be a 1-character string
     """
+    # `_open_output_file` replaces filesystem paths with writable text streams.
     assert not isinstance(output_csv_file, (str, bytes, os.PathLike))
     output_file = output_csv_file
     csv_writer = csv.writer(output_file, delimiter=col_separator, lineterminator=row_separator)
@@ -374,6 +375,7 @@ def write_scene_list_edl(
             every event so the EDL aligns with the source media's on-screen timecode. Applied to
             both source and record columns.
     """
+    # `_open_output_file` replaces filesystem paths with writable text streams.
     assert not isinstance(output_path, (str, bytes, os.PathLike))
     output_file = output_path
     offset_frames = 0
@@ -436,6 +438,7 @@ def write_scene_list_fcpx(
             of `video_path`.
     """
     assert scene_list
+    # `_open_output_file` replaces filesystem paths with writable text streams.
     assert not isinstance(output_path, (str, bytes, os.PathLike))
     output_file = output_path
     video_path = Path(video_path)
@@ -540,6 +543,7 @@ def write_scene_list_fcp7(
             frozen. If None, falls back to the last scene's end time.
     """
     assert scene_list
+    # `_open_output_file` replaces filesystem paths with writable text streams.
     assert not isinstance(output_path, (str, bytes, os.PathLike))
     output_file = output_path
     video_path = Path(video_path)
@@ -654,6 +658,7 @@ def write_scene_list_otio(
         name: Timeline name. Defaults to the stem of `video_path`.
         audio: If True (default), include an audio track alongside the video track.
     """
+    # `_open_output_file` replaces filesystem paths with writable text streams.
     assert not isinstance(output_path, (str, bytes, os.PathLike))
     output_file = output_path
     video_path = Path(video_path)

tests/test_output.py

@@ -32,6 +32,7 @@
 from scenedetect.output import (
     SceneMetadata,
     VideoMetadata,
+    _open_output_file,
     is_ffmpeg_available,
     split_video_ffmpeg,
     write_scene_list,
@@ -273,6 +274,20 @@ def _make_output_target(
     return output_target, lambda: output_path.read_text(encoding="utf-8")
 
 
+def test_open_output_file_does_not_create_file_on_error(tmp_path: Path):
+    """The decorator does not create a destination when output generation fails."""
+
+    @_open_output_file("TEST")
+    def failing_writer(output_file: ty.Any):
+        output_file.write("partial output")
+        raise RuntimeError("generation failed")
+
+    output_path = tmp_path / "output.txt"
+    with pytest.raises(RuntimeError, match="generation failed"):
+        failing_writer(output_path)
+    assert not output_path.exists()
+
+
 @pytest.mark.parametrize("target_kind", _OUTPUT_TARGET_KINDS)
 def test_write_scene_list_output_target(tmp_path: Path, target_kind: str):
     """CSV output accepts a file handle, string, Path, or bytes path."""