How do you assert that a certain exception is thrown in JUnit tests?

Question

How can I use JUnit idiomatically to test that some code throws an exception?

While I can certainly do something like this:

@Test
public void testFooThrowsIndexOutOfBoundsException() {

    boolean thrown = false;

    try {
        foo.doStuff();
    } catch (IndexOutOfBoundsException e) {
        thrown = true;
    }

    assertTrue(thrown);
}

I recall that there is an annotation or an Assert.xyz or something that is far less kludgy and far more in-the-spirit of JUnit for these sorts of situations.

Answer 1

It depends on the JUnit version and what assert libraries you use.

• For JUnit5 and 4.13 see answer
• If you use AssertJ or google-truth, see answer

The original answer for JUnit <= 4.12 was:

    @Test(expected = IndexOutOfBoundsException.class)
    public void testIndexOutOfBoundsException() {

        ArrayList emptyList = new ArrayList();
        Object o = emptyList.get(0);

    }

Though answer has more options for JUnit <= 4.12.

Reference:

• JUnit Test-FAQ