Fix --field-order opt parsing.

It was parsing the enum value instead of the name.

Fixes #33

src/tbc_video_export/opts/opts_ffmpeg.py

@@ -133,7 +133,7 @@ def add_ffmpeg_opts(config: Config, parent: argparse.ArgumentParser) -> None:
 
     ffmpeg_opts.add_argument(
         "--field-order",
-        type=FieldOrder,
+        type=_TypeFieldOrder(parent),
         choices=list(FieldOrder),
         default=FieldOrder.TFF,
         metavar="order",
@@ -250,6 +250,21 @@ def __call__(
         parser.exit()
 
 
+class _TypeFieldOrder:
+    """Return FieldOrder value if it exists."""
+
+    def __init__(self, parser: argparse.ArgumentParser) -> None:
+        self._parser = parser
+
+    def __call__(self, value: str) -> FieldOrder:
+        try:
+            return FieldOrder[value.upper()]
+        except KeyError:
+            self._parser.error(
+                f"argument --field-order: invalid FieldOrder value: '{value}'"
+            )
+
+
 def _check_metadata_file_exists(value: str) -> Path:
     """Return metadata path if it exists."""
     if (path := Path(value)).is_file():

tests/test_wrappers_ffmpeg.py

@@ -2,7 +2,9 @@
 
 import unittest
 from functools import partial
+from io import StringIO
 from pathlib import Path
+from unittest.mock import patch
 
 from tbc_video_export.common.enums import TBCType
 from tbc_video_export.common.file_helper import FileHelper
@@ -137,6 +139,59 @@ def test_ffmpeg_metadata_opts(self) -> None:  # noqa: D102
         self.assertTrue({"-metadata", "foo=bar"}.issubset(cmd))
         self.assertTrue({"-metadata", "bar=foo"}.issubset(cmd))
 
+    def test_ffmpeg_default_field_order_opt(self) -> None:  # noqa: D102
+        _, opts = self.parse_opts([str(self.path), "pal_svideo"])
+        self.files = FileHelper(opts, self.config)
+        state = ProgramState(opts, self.config, self.files)
+
+        ffmpeg_wrapper = WrapperFFmpeg(
+            state,
+            WrapperConfig[tuple[Pipe], None](
+                state.current_export_mode,
+                TBCType.CHROMA,
+                input_pipes=(self.pipe, self.pipe),
+                output_pipes=None,
+            ),
+        )
+
+        cmd = ffmpeg_wrapper.command.data
+
+        self.assertTrue(any("setfield=tff" in cmds for cmds in cmd))
+
+    def test_ffmpeg_field_order_opt(self) -> None:  # noqa: D102
+        _, opts = self.parse_opts(
+            [str(self.path), "pal_svideo", "--field-order", "bff"]
+        )
+        self.files = FileHelper(opts, self.config)
+        state = ProgramState(opts, self.config, self.files)
+
+        ffmpeg_wrapper = WrapperFFmpeg(
+            state,
+            WrapperConfig[tuple[Pipe], None](
+                state.current_export_mode,
+                TBCType.CHROMA,
+                input_pipes=(self.pipe, self.pipe),
+                output_pipes=None,
+            ),
+        )
+
+        cmd = ffmpeg_wrapper.command.data
+
+        self.assertTrue(any("setfield=bff" in cmds for cmds in cmd))
+
+    @patch("sys.stderr", new_callable=StringIO)
+    def test_ffmpeg_field_order_invalid_opt(self, mock_stderr: StringIO) -> None:  # noqa: D102
+        # invalid option
+        with self.assertRaises(SystemExit):
+            _, __ = self.parse_opts(
+                [str(self.path), "pal_svideo", "--field-order", "invalid"]
+            )
+
+        self.assertRegex(
+            mock_stderr.getvalue(),
+            r"error: argument --field-order: invalid FieldOrder value: 'invalid'",
+        )
+
 
 if __name__ == "__main__":
     unittest.main()