junit 4中对指定异常的测试
junit 4中，也可以测试指定的异常是否出现了，比如：

public class Person {  private final String name;  private final int age;    public Person(String name, int age) {    this.name = name;    this.age = age;    if (age <= 0) {      throw new IllegalArgumentException('Invalid age:' + age);    }  }}

要测试是否IllegalArgumentException抛出了，则可以使用注解的annotation:

import static org.hamcrest.Matchers.*;import static org.junit.Assert.*;import org.junit.Rule;import org.junit.Test;import org.junit.rules.ExpectedException;public class PersonTest {  @Rule  public ExpectedException exception = ExpectedException.none();  @Test  public void testExpectedException() {    exception.expect(IllegalArgumentException.class);    exception.expectMessage(containsString('Invalid age'));    new Person('Joe', -1);  }}

但很奇怪，居然不能这样：

@Test(expected = IllegalArgumentException.class)public void testExpectedException2() {  new Person('Joe', -1);}