'A ``ConfigurationError`` is raised if the "environment" dictionary
in a fig application config contains a key whose value is not of
``types.StringTypes``.'

def test_invalid_fig_config_env_not_stringtypes(self):

    config = {u'postgres': {u'environment': {u'PG_ROOT_PASSWORD': [u'a', u'b', u'c']}, u'image': u'sample/postgres', u'ports': [u'54320:5432'], u'volumes': [u'/var/lib/postgres']}}
    parser = FigConfiguration(config)
    exception = self.assertRaises(ConfigurationError, parser.applications)
    error_message = u"Application    'postgres'    has    a    config    error.    'environment'    value    for    'PG_ROOT_PASSWORD'    must    be    a    string;    got    type    'list'."
    self.assertEqual(exception.message, error_message)
