Convert mb_artistid and mb_albumartistid to multivalue

Resolves beetbox#43

Author: JuniorJPDJ

mediafile.py

@@ -1947,16 +1947,17 @@ def update(self, dict):
         StorageStyle('MUSICBRAINZ_ALBUMID'),
         ASFStorageStyle('MusicBrainz/Album Id'),
     )
-    mb_artistid = MediaField(
-        MP3DescStorageStyle(u'MusicBrainz Artist Id'),
-        MP4StorageStyle('----:com.apple.iTunes:MusicBrainz Artist Id'),
-        StorageStyle('MUSICBRAINZ_ARTISTID'),
+    mb_artistid = ListMediaField(
+        MP3ListDescStorageStyle(u'MusicBrainz Artist Id'),
+        MP4ListStorageStyle('----:com.apple.iTunes:MusicBrainz Artist Id'),
+        ListStorageStyle('MUSICBRAINZ_ARTISTID'),
         ASFStorageStyle('MusicBrainz/Artist Id'),
     )
-    mb_albumartistid = MediaField(
-        MP3DescStorageStyle(u'MusicBrainz Album Artist Id'),
-        MP4StorageStyle('----:com.apple.iTunes:MusicBrainz Album Artist Id'),
-        StorageStyle('MUSICBRAINZ_ALBUMARTISTID'),
+    mb_albumartistid = ListMediaField(
+        MP3ListDescStorageStyle(u'MusicBrainz Album Artist Id'),
+        MP4ListStorageStyle(
+            '----:com.apple.iTunes:MusicBrainz Album Artist Id'),
+        ListStorageStyle('MUSICBRAINZ_ALBUMARTISTID'),
         ASFStorageStyle('MusicBrainz/Album Artist Id'),
     )
     mb_releasegroupid = MediaField(

test/test_mediafile.py

@@ -340,7 +340,7 @@ class ReadWriteTestBase(ArtTestMixin, GenreListTestMixin,
         'mb_trackid':        '8b882575-08a5-4452-a7a7-cbb8a1531f9e',
         'mb_releasetrackid': 'c29f3a57-b439-46fd-a2e2-93776b1371e0',
         'mb_albumid':        '9e873859-8aa4-4790-b985-5a953e8ef628',
-        'mb_artistid':       '7cf0ea9d-86b9-4dad-ba9e-2355a64899ea',
+        'mb_artistid':       ['7cf0ea9d-86b9-4dad-ba9e-2355a64899ea'],
         'art':               None,
         'label':             u'the label',
     }
@@ -371,7 +371,6 @@ class ReadWriteTestBase(ArtTestMixin, GenreListTestMixin,
         'mb_releasetrackid',
         'mb_workid',
         'mb_albumid',
-        'mb_artistid',
         'art',
         'label',
         'rg_track_peak',
@@ -381,7 +380,6 @@ class ReadWriteTestBase(ArtTestMixin, GenreListTestMixin,
         'r128_track_gain',
         'r128_album_gain',
         'albumartist',
-        'mb_albumartistid',
         'artist_sort',
         'albumartist_sort',
         'acoustid_fingerprint',
@@ -449,7 +447,11 @@ def test_read_full(self):
     def test_read_empty(self):
         mediafile = self._mediafile_fixture('empty')
         for field in self.tag_fields:
-            self.assertIsNone(getattr(mediafile, field))
+            value = getattr(mediafile, field)
+            if isinstance(value, list):
+                assert len(value) == 0
+            else:
+                self.assertIsNone(value)
 
     def test_write_empty(self):
         mediafile = self._mediafile_fixture('empty')
@@ -620,7 +622,11 @@ def test_delete_tag(self):
         mediafile = MediaFile(mediafile.path)
 
         for key in keys:
-            self.assertIsNone(getattr(mediafile, key))
+            value = getattr(mediafile, key)
+            if isinstance(value, list):
+                assert len(value) == 0
+            else:
+                self.assertIsNone(value)
 
     def test_delete_packed_total(self):
         mediafile = self._mediafile_fixture('full')
@@ -705,6 +711,9 @@ def _generate_tags(self, base=None):
         for key in ['disc', 'disctotal', 'track', 'tracktotal', 'bpm']:
             tags[key] = 1
 
+        for key in ['mb_artistid', 'mb_albumartistid']:
+            tags[key] = ['multival', 'test']
+
         tags['art'] = self.jpg_data
         tags['comp'] = True
 
@@ -976,7 +985,8 @@ def test_properties_from_readable_fields(self):
 
     def test_known_fields(self):
         fields = list(ReadWriteTestBase.tag_fields)
-        fields.extend(('encoder', 'images', 'genres', 'albumtype'))
+        fields.extend(('encoder', 'images', 'genres', 'albumtype',
+                       'mb_artistid', 'mb_albumartistid'))
         assertCountEqual(self, MediaFile.fields(), fields)
 
     def test_fields_in_readable_fields(self):