The test suite does not take the constraints into account such as,

280) Error: test_users_from_fixtures_should_have_correct_roles(UserTest?): ActiveRecord?::StatementInvalid?: Mysql::Error:
Cannot delete or update a parent row: a foreign key constraint fails (smc_test/groups, CONSTRAINT groups_ibfk_1 FOREIGN
KEY (parent_id) REFERENCES groups (id) ON UPDATE NO ACTION): DELETE FROM groups

(Rails 1.1.4)