'Test construction from list of namespaces.'

def test_from_namespaces(self):

    self.assertEqual(RegexSet.from_namespaces([]), RegexSet([], []))
    self.assertEqual(RegexSet.from_namespaces(['db.bar', 'db_*.foo', 'db2.*']), RegexSet([namespace_to_regex('db_*.foo'), namespace_to_regex('db2.*')], ['db.bar']))
