'A ``MissingMigrationError`` is raised if a migration path
from one version to another cannot be found in the supplied
migration class.'

def test_error_on_undefined_migration_path(self):

    e = self.assertRaises(MissingMigrationError, migrate_configuration, 1, 4, self.v1_config, StubMigration)
    expected_error = u'Unable    to    find    a    migration    path    for    a    version    3    to    version    4    configuration.    No    migration    method    upgrade_from_v3    could    be    found.'
    self.assertEqual(e.message, expected_error)
