Discogs featured artist fix (#6040)

Fixes #6038 - Appends featured artists in the extraartists field to the
artist tag, similar to the MusicBrainz plugin. Works well with ftintitle
for consistency as well.

## To Do

May need adjustment for common artist delimiters used - but appears to
match the MusicBrainz standard at the moment.

Author: snejus

beetsplug/discogs.py

@@ -339,7 +339,7 @@ def get_album_info(self, result):
         # convenient `.tracklist` property, which will strip out useful artist
         # information and leave us with skeleton `Artist` objects that will
         # each make an API call just to get the same data back.
-        tracks = self.get_tracks(result.data["tracklist"])
+        tracks = self.get_tracks(result.data["tracklist"], artist, artist_id)
 
         # Extract information for the optional AlbumInfo fields, if possible.
         va = result.data["artists"][0].get("name", "").lower() == "various"
@@ -386,10 +386,6 @@ def get_album_info(self, result):
         for track in tracks:
             track.media = media
             track.medium_total = mediums.count(track.medium)
-            if not track.artist:  # get_track_info often fails to find artist
-                track.artist = artist
-            if not track.artist_id:
-                track.artist_id = artist_id
             # Discogs does not have track IDs. Invent our own IDs as proposed
             # in #2336.
             track.track_id = f"{album_id}-{track.track_alt}"
@@ -446,7 +442,7 @@ def format(self, classification):
         else:
             return None
 
-    def get_tracks(self, tracklist):
+    def get_tracks(self, tracklist, album_artist, album_artist_id):
         """Returns a list of TrackInfo objects for a discogs tracklist."""
         try:
             clean_tracklist = self.coalesce_tracks(tracklist)
@@ -471,7 +467,9 @@ def get_tracks(self, tracklist):
                     # divisions.
                     divisions += next_divisions
                     del next_divisions[:]
-                track_info = self.get_track_info(track, index, divisions)
+                track_info = self.get_track_info(
+                    track, index, divisions, album_artist, album_artist_id
+                )
                 track_info.track_alt = track["position"]
                 tracks.append(track_info)
             else:
@@ -638,7 +636,9 @@ def strip_disambiguation(self, text: str) -> str:
             return text
         return DISAMBIGUATION_RE.sub("", text)
 
-    def get_track_info(self, track, index, divisions):
+    def get_track_info(
+        self, track, index, divisions, album_artist, album_artist_id
+    ):
         """Returns a TrackInfo object for a discogs track."""
         title = track["title"]
         if self.config["index_tracks"]:
@@ -650,8 +650,21 @@ def get_track_info(self, track, index, divisions):
         artist, artist_id = self.get_artist(
             track.get("artists", []), join_key="join"
         )
-        artist = self.strip_disambiguation(artist)
+        # If no artist and artist is returned, set to match album artist
+        if not artist:
+            artist = album_artist
+            artist_id = album_artist_id
         length = self.get_track_length(track["duration"])
+        # Add featured artists
+        extraartists = track.get("extraartists", [])
+        featured = [
+            artist["name"]
+            for artist in extraartists
+            if "Featuring" in artist["role"]
+        ]
+        if featured:
+            artist = f"{artist} feat. {', '.join(featured)}"
+        artist = self.strip_disambiguation(artist)
         return TrackInfo(
             title=title,
             track_id=track_id,

docs/changelog.rst

@@ -15,6 +15,7 @@ New features:
   converted files.
 - :doc:`plugins/discogs`: New config option `strip_disambiguation` to toggle
   stripping discogs numeric disambiguation on artist and label fields.
+- :doc:`plugins/discogs` Added support for featured artists.
 
 Bug fixes:
 
@@ -27,6 +28,8 @@ Bug fixes:
   matching. :bug:`5189`
 - :doc:`plugins/discogs` Fixed inconsistency in stripping disambiguation from
   artists but not labels. :bug:`5366`
+- :doc:`plugins/discogs` Fixed issue with ignoring featured artists in the
+  extraartists field.
 - :doc:`plugins/spotify` Fixed an issue where candidate lookup would not find
   matches due to query escaping (single vs double quotes).
 

test/plugins/test_discogs.py

@@ -450,6 +450,52 @@ def test_strip_disambiguation_false(self):
         assert d.artist == "ARTIST NAME (2) & OTHER ARTIST (5)"
         assert d.tracks[0].artist == "TEST ARTIST (5)"
         assert d.label == "LABEL NAME (5)"
+        config["discogs"]["strip_disambiguation"] = True
+
+
+@pytest.mark.parametrize(
+    "track, expected_artist",
+    [
+        (
+            {
+                "type_": "track",
+                "title": "track",
+                "position": "1",
+                "duration": "5:00",
+                "artists": [
+                    {"name": "NEW ARTIST", "tracks": "", "id": 11146},
+                    {"name": "VOCALIST", "tracks": "", "id": 344, "join": "&"},
+                ],
+                "extraartists": [
+                    {
+                        "name": "SOLOIST",
+                        "role": "Featuring",
+                    },
+                    {
+                        "name": "PERFORMER (1)",
+                        "role": "Other Role, Featuring",
+                    },
+                    {
+                        "name": "RANDOM",
+                        "role": "Written-By",
+                    },
+                    {
+                        "name": "MUSICIAN",
+                        "role": "Featuring [Uncredited]",
+                    },
+                ],
+            },
+            "NEW ARTIST, VOCALIST feat. SOLOIST, PERFORMER, MUSICIAN",
+        ),
+    ],
+)
+@patch("beetsplug.discogs.DiscogsPlugin.setup", Mock())
+def test_parse_featured_artists(track, expected_artist):
+    """Tests the plugins ability to parse a featured artist.
+    Initial check with one featured artist, two featured artists,
+    and three. Ignores artists that are not listed as featured."""
+    t = DiscogsPlugin().get_track_info(track, 1, 1, "ARTIST", 2)
+    assert t.artist == expected_artist
 
 
 @pytest.mark.parametrize(