Take into account va_likely param and remove redundant checks

- Instead of checking for empty `artist` query, use `va_likely`
  parameter to determine whether we should query for Various Artists or
  not.
- `album` / `title` is always a truthy string - no need to handle empty
  criteria case
- `tracks` list always has at least one track - no need to check for
  `len(items)`

beetsplug/musicbrainz.py

@@ -768,15 +768,14 @@ class MusicBrainzPlugin(BeetsPlugin):
     def get_album_criteria(
         self, items: list[Item], artist: str, album: str, va_likely: bool
     ) -> dict[str, str]:
-        # Build search criteria.
-        criteria = {"release": album.lower().strip()}
-        if artist is not None:
-            criteria["artist"] = artist.lower().strip()
-        else:
-            # Various Artists search.
-            criteria["arid"] = VARIOUS_ARTISTS_ID
-        if track_count := len(items):
-            criteria["tracks"] = str(track_count)
+        criteria = {
+            "release": album.lower().strip(),
+            "tracks": str(len(items)),
+        } | (
+            {"arid": VARIOUS_ARTISTS_ID}
+            if va_likely
+            else {"artist": artist.lower().strip()}
+        )
 
         for tag, mb_field in self.extra_mb_field_by_tag.items():
             most_common, _ = util.plurality(i.get(tag) for i in items)
@@ -804,9 +803,6 @@ class MusicBrainzPlugin(BeetsPlugin):
         optionally, a number of tracks on the album and any other extra tags.
         """
         criteria = self.get_album_criteria(items, artist, album, va_likely)
-        # Abort if we have no search terms.
-        if not any(criteria.values()):
-            return
 
         try:
             self._log.debug(
@@ -837,9 +833,6 @@ class MusicBrainzPlugin(BeetsPlugin):
             "recording": title.lower().strip(),
         }
 
-        if not any(criteria.values()):
-            return
-
         try:
             res = musicbrainzngs.search_recordings(
                 limit=self.config["searchlimit"].get(int), **criteria

test/plugins/test_musicbrainz.py

@@ -823,23 +823,13 @@ class MBLibraryTest(MusicBrainzTestCase):
 
                 ai = list(self.mb.candidates([], "hello", "there", False))[0]
 
-                sp.assert_called_with(artist="hello", release="there", limit=5)
+                sp.assert_called_with(
+                    artist="hello", release="there", tracks="0", limit=5
+                )
                 gp.assert_called_with(mbid, mock.ANY)
                 assert ai.tracks[0].title == "foo"
                 assert ai.album == "hi"
 
-    def test_match_track_empty(self):
-        with mock.patch("musicbrainzngs.search_recordings") as p:
-            til = list(self.mb.item_candidates(None, " ", " "))
-            assert not p.called
-            assert til == []
-
-    def test_candidates_empty(self):
-        with mock.patch("musicbrainzngs.search_releases") as p:
-            ail = list(self.mb.candidates([], " ", " ", False))
-            assert not p.called
-            assert ail == []
-
     def test_follow_pseudo_releases(self):
         side_effect = [
             {