How do you assert that a certain exception is thrown in JUnit 4 tests?

Question

How can I use JUnit4 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 https://stackoverflow.com/a/2935935/2986984
• If you use assertJ or google-truth, see answer https://stackoverflow.com/a/41019785/2986984

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 https://stackoverflow.com/a/31826781/2986984 has more options for JUnit <= 4.12.

Reference :

• JUnit Test-FAQ