Accompaniment

tests/test_acoustic.py

@@ -131,7 +131,10 @@ class AcousticTests(unittest.TestCase):
       combined = builder(source, 'acoustic')
       self.assertEqual(sounding(separate), sounding(combined))
       generator.model.validate_document(combined)
-      self.assertTrue(all(len(m['voices']) == 1 for m in combined['staves'][0]['measures']))
+      for measure in combined['staves'][0]['measures']:
+        self.assertIn(len(measure['voices']), (1, 2))
+        if len(measure['voices']) == 2:
+          self.assertEqual({v['id'] for v in measure['voices']}, {'upper', 'bass'})
   def test_engraved_chord_has_one_stem_and_no_competing_rests(self):
     document = acoustic_document([([(0, 4)], [(1, 2), (3, 1)])])
     self.combine(document)