'``Configuration.applications`` raises a
``ConfigurationError`` if the application_configuration does not
contain an ``u"application"`` key.'

def test_error_on_missing_application_key(self):

    config = dict()
    parser = FlockerConfiguration(config)
    exception = self.assertRaises(ConfigurationError, parser.applications)
    self.assertEqual(u"Application    configuration    has    an    error.    Missing    'applications'    key.", exception.message)
