used to work due to inconsistent mediafile implementation, but with
https://github.com/beetbox/mediafile/pull/64 (in mediafile >= 0.11.0)
list fields are None if non-existent, not the empty list

Upstream-PR: https://github.com/beetbox/beets/pull/4593

diff --git a/test/test_embedart.py b/test/test_embedart.py
index 6b6d616..bc550a8 100644
--- a/test/test_embedart.py
+++ b/test/test_embedart.py
@@ -81,7 +81,7 @@ class EmbedartCliTest(_common.TestCase, TestHelper):
         self.run_command('embedart', '-f', self.small_artpath)
         mediafile = MediaFile(syspath(item.path))
         # make sure that images array is empty (nothing embedded)
-        self.assertEqual(len(mediafile.images), 0)
+        self.assertFalse(mediafile.images)
 
     def test_embed_art_from_file(self):
         self._setup_data()
@@ -202,7 +202,7 @@ class EmbedartCliTest(_common.TestCase, TestHelper):
         self.io.addinput('y')
         self.run_command('clearart')
         mediafile = MediaFile(syspath(item.path))
-        self.assertEqual(len(mediafile.images), 0)
+        self.assertFalse(mediafile.images)
 
     def test_clear_art_with_no_input(self):
         self._setup_data()
diff --git a/test/test_zero.py b/test/test_zero.py
index c4c1769..b48367b 100644
--- a/test/test_zero.py
+++ b/test/test_zero.py
@@ -103,7 +103,7 @@ class ZeroPluginTest(unittest.TestCase, TestHelper):
         item.write()
 
         mf = MediaFile(syspath(path))
-        self.assertEqual(0, len(mf.images))
+        self.assertFalse(mf.images)
 
     def test_auto_false(self):
         self.config['zero']['fields'] = ['year']