@Test(expected = IllegalArgumentException.class)
public void twoRulesWithSameHighestPriorityIsNotAllowed() {

    conditionalRuleGroup.addRule(new MyOtherRule(0));// same priority as conditionalRule
    conditionalRuleGroup.addRule(new MyOtherRule(1));
    conditionalRuleGroup.addRule(new MyRule());
    conditionalRuleGroup.evaluate(facts);
}