Fix extension issue in convert plugin when exporting a playlist

beetsplug/convert.py

@@ -604,6 +604,8 @@ def convert_func(self, lib, opts, args):
             items,
         )
 
+        # If the user supplied a playlist name, create a playlist containing
+        # all converted titles using this name.
         if playlist:
             # Playlist paths are understood as relative to the dest directory.
             pl_normpath = util.normpath(playlist)
@@ -615,10 +617,15 @@ def convert_func(self, lib, opts, args):
             items_paths = [
                 os.path.relpath(
                     util.bytestring_path(
-                        item.destination(
-                            basedir=dest,
-                            path_formats=path_formats,
-                            fragment=False,
+                        # Substitute the before-conversion file extension by
+                        # the after-conversion extension.
+                        replace_ext(
+                            item.destination(
+                                basedir=dest,
+                                path_formats=path_formats,
+                                fragment=False,
+                            ),
+                            get_format()[1],
                         )
                     ),
                     pl_dir,

docs/changelog.rst

@@ -510,6 +510,8 @@ Bug fixes:
   `requests` timeout.
 * Fix cover art resizing logic to support multiple steps of resizing
   :bug:`5151`
+* :doc:`/plugins/convert`: Fix extension substitution inside path of the
+  exported playlist.
 
 For plugin developers:
 

test/plugins/test_convert.py

@@ -298,6 +298,19 @@ def test_playlist_pretend(self):
         m3u_created = os.path.join(self.convert_dest, b"playlist.m3u8")
         assert not os.path.exists(m3u_created)
 
+    def test_playlist_ext(self):
+        """Test correct extension of file inside the playlist when format
+        conversion occurs."""
+        # We expect a converted file with the MP3 extension.
+        self.config["convert"]["format"] = "mp3"
+        with control_stdin("y"):
+            self.run_convert("--playlist", "playlist.m3u8")
+            # Check playlist content.
+            m3u_created = os.path.join(self.convert_dest, b"playlist.m3u8")
+            with open(m3u_created, "r") as m3u_file:
+                assert m3u_file.readline() == "#EXTM3U\n"
+                assert m3u_file.readline() == "converted.mp3\n"
+
 
 @_common.slow_test()
 class NeverConvertLossyFilesTest(ConvertTestCase, ConvertCommand):