'An entry in a list of environment variables that is just a label is
mapped to its label and a value of an empty unicode string.'

def test_fig_config_environment_list_item_empty_value(self):

    config = {u'postgres': {u'environment': [u'PGSQL_PORT_EXTERNAL=54320', u'PGSQL_USER_PASSWORD'], u'image': u'sample/postgres', u'ports': [u'54320:5432'], u'volumes': [u'/var/lib/postgres']}}
    parser = FigConfiguration(config)
    result = parser._parse_app_environment(u'postgres', config[u'postgres'][u'environment'])
    expected = frozenset([(u'PGSQL_PORT_EXTERNAL', u'54320'), (u'PGSQL_USER_PASSWORD', u'')])
    self.assertEqual(expected, result)
