假如需要测试下面的类：

public class Student {
  public boolean canVote(int age) {
      if (i<=0) throw new IllegalArgumentException("age should be +");
      if (i<18) return false;
      else return true;
测试抛出的异常有三种方法：
@Test ( expected = Throwable.class )
@Test(expected = IllegalArgumentException.class)
public void canVoteExp() {
    Student student = new Student();
    student.canVote(0);
这种测试有一点误差，因为异常会在方法的某个位置被抛出，但不一定在特定的某行。
ExpectedException

如果要使用JUnit框架中的ExpectedException类，需要声明ExpectedException异常。
@Rule

public ExpectedException thrown = ExpectedException.none();
然后可以使用更加简单的方式验证预期的异常
@Test
public void canVoteExp() {
    Student student = new Student();
    thrown.expect(IllegalArgumentException.class);
    student.canVote(0);
还可以设置预期异常的属性信息
@Test
public void canVoteExp() {
    Student student = new Student();
    thrown.expect(IllegalArgumentException.class);
    thrown.expectMessage("age should be +");
    student.canVote(0);
这种方法可以更加精确的找到异常抛出的位置。
try/catch with assert/fail

在JUnit4之前的版本中，使用try/catch语句块检查异常
@Test
public void canVoteExp() {
    Student student = new Student();
    try {
        student.canVote(0);
    } catch (IllegalArgumentException e) {
        assertThat(e.getMessage(), containsString("age should be +"));