class ConcurrentErrorTest extends GroovyTestCase {
	void testError(){
		shouldFail(ConcurrentModificationException){
			def list = [1,2,3]
			list.eachWithIndex{e, i->
				list.remove(i)
			}
		}
	}
}

Groovy save you from using try/catch that expect exception in junit.

Quick Unit Testing

Groovy