old_contents: import unittest
  
  from mopidy_spotify import Extension, backend as backend_lib
  
  
  class ExtensionTest(unittest.TestCase):
  
      def test_get_default_config(self):
          ext = Extension()
  
          config = ext.get_default_config()
  
          self.assertIn('[spotify]', config)
          self.assertIn('enabled = true', config)
  
      def test_get_config_schema(self):
          ext = Extension()
  
          schema = ext.get_config_schema()
  
          self.assertIn('username', schema)
          self.assertIn('password', schema)
          self.assertIn('bitrate', schema)
          self.assertIn('timeout', schema)
          self.assertIn('cache_dir', schema)
  
      def test_get_backend_classes(self):
          ext = Extension()
  
          backends = ext.get_backend_classes()
  
          self.assertIn(backend_lib.SpotifyBackend, backends)
  
new_contents: import mock, unittest
  
  from mopidy_spotify import Extension, backend as backend_lib
  
  
  class ExtensionTest(unittest.TestCase):
  
      def test_get_default_config(self):
          ext = Extension()
  
          config = ext.get_default_config()
  
          self.assertIn('[spotify]', config)
          self.assertIn('enabled = true', config)
  
      def test_get_config_schema(self):
          ext = Extension()
  
          schema = ext.get_config_schema()
  
          self.assertIn('username', schema)
          self.assertIn('password', schema)
          self.assertIn('bitrate', schema)
          self.assertIn('timeout', schema)
          self.assertIn('cache_dir', schema)
  
      def test_setup(self):
          registry = mock.Mock()
  
          ext = Extension()
          ext.setup(registry)
  
          registry.add.assert_called_with('backend', backend_lib.SpotifyBackend)
  
subject: Test extension with mock registry