PICARD-711: Add support for series variables

Adds support for variables for release group, release, recording
and work series. The following variables are getting set:

- ~recording_series
- ~recording_series_id
- ~recording_seriescomment
- ~recording_seriesnumber
- ~release_series
- ~release_series_id
- ~release_seriescomment
- ~release_seriesnumber
- ~releasegroup_series
- ~releasegroup_series_id
- ~releasegroup_seriescomment
- ~releasegroup_seriesnumber
- ~work_series
- ~work_series_id
- ~work_seriescomment
- ~work_seriesnumber

test/test_mbjson.py

@@ -5,7 +5,7 @@
 # Copyright (C) 2017 Sambhav Kothari
 # Copyright (C) 2017, 2019-2022 Laurent Monin
 # Copyright (C) 2018 Wieland Hoffmann
-# Copyright (C) 2018-2022 Philipp Wolfer
+# Copyright (C) 2018-2023 Philipp Wolfer
 # Copyright (C) 2020 dukeyin
 # Copyright (C) 2021 Bob Swift
 # Copyright (C) 2021 Vladislav Karbovskii
@@ -123,6 +123,10 @@ class ReleaseTest(MBJSONTest):
         self.assertEqual(m['~releaseannotation'], 'Original Vinyl release')
         self.assertEqual(m['~releaselanguage'], 'eng')
         self.assertEqual(m.getall('~releasecountries'), ['GB', 'NZ'])
+        self.assertEqual(m['~release_series'], 'Why Pink Floyd?')
+        self.assertEqual(m['~release_seriesid'], '7421b602-a413-4151-bcf4-d831debc3f27')
+        self.assertEqual(m['~release_seriescomment'], 'Pink Floyed special editions')
+        self.assertEqual(m['~release_seriesnumber'], '')
         self.assertEqual(a.genres, {
             'genre1': 6, 'genre2': 3,
             'tag1': 6, 'tag2': 3})
@@ -178,6 +182,22 @@ class ReleaseTest(MBJSONTest):
         formats = media_formats_from_node(self.json_doc['media'])
         self.assertEqual(formats, '12" Vinyl')
 
+    def test_release_group_rels(self):
+        m = Metadata()
+        release_group_to_metadata(self.json_doc['release-group'], m)
+        self.assertEqual(m.getall('~releasegroup_series'), [
+            "Absolute Radio's The 100 Collection",
+            '1001 Albums You Must Hear Before You Die'
+        ])
+        self.assertEqual(m.getall('~releasegroup_seriesid'), [
+            '4bf41050-6fa9-41a6-8398-15bdab4b0352',
+            '4bc2a338-e1d8-4546-8a61-640da8aaf888'
+        ])
+        self.assertEqual(m.getall('~releasegroup_seriescomment'), [
+            '2005 edition'
+        ])
+        self.assertEqual(m.getall('~releasegroup_seriesnumber'), ['15', '291'])
+
 
 class NullReleaseTest(MBJSONTest):