old_contents: from __future__ import unicode_literals
  
  from mopidy import exceptions
  
  from tests import unittest
  
  
  class ExceptionsTest(unittest.TestCase):
      def test_exception_can_include_message_string(self):
          exc = exceptions.MopidyException('foo')
  
          self.assertEqual(exc.message, 'foo')
          self.assertEqual(str(exc), 'foo')
  
      def test_settings_error_is_a_mopidy_exception(self):
          self.assert_(issubclass(
              exceptions.SettingsError, exceptions.MopidyException))
  
      def test_optional_dependency_error_is_a_mopidy_exception(self):
          self.assert_(issubclass(
              exceptions.OptionalDependencyError, exceptions.MopidyException))
  
      def test_extension_error_is_a_mopidy_exception(self):
          self.assert_(issubclass(
              exceptions.ExtensionError, exceptions.MopidyException))
  
new_contents: from __future__ import unicode_literals
  
  from mopidy import exceptions
  
  from tests import unittest
  
  
  class ExceptionsTest(unittest.TestCase):
      def test_exception_can_include_message_string(self):
          exc = exceptions.MopidyException('foo')
  
          self.assertEqual(exc.message, 'foo')
          self.assertEqual(str(exc), 'foo')
  
      def test_settings_error_is_a_mopidy_exception(self):
          self.assert_(issubclass(
              exceptions.SettingsError, exceptions.MopidyException))
  
      def test_optional_dependency_error_is_a_mopidy_exception(self):
          self.assert_(issubclass(
              exceptions.OptionalDependencyError, exceptions.MopidyException))
  
      def test_extension_error_is_a_mopidy_exception(self):
          self.assert_(issubclass(
              exceptions.ExtensionError, exceptions.MopidyException))
  
      def test_config_error_is_a_mopidy_exception(self):
          self.assert_(issubclass(
              exceptions.ConfigError, exceptions.MopidyException))
  
      def test_config_error_provides_getitem(self):
          exception = exceptions.ConfigError({'field1': 'msg1', 'field2': 'msg2'})
          self.assertEqual('msg1', exception['field1'])
          self.assertEqual('msg2', exception['field2'])
          self.assertItemsEqual(['field1', 'field2'], exception)
  
subject: Add ConfigError test.