Reinventing shouldFail() part2

gistfile1.groovy

import groovy.util.GroovyTestCase

public class Test extends GroovyTestCase {

    private shouldFailBy(Class expected, Closure c) {
        try {
            c.call()
            assert false // Failure
        } catch (Throwable t) {
            assert expected.isInstance(t)
        }
    }

    public void test() {
        shouldFailBy (NullPointerException) {throw new NullPointerException()}
        shouldFailBy (IllegalAccessError) {throw new IllegalAccessError()}
    }

}