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 testFo         


        

Answer 1

I tried many of the methods here, but they were either complicated or didn't quite meet my requirements. In fact, one can write a helper method quite simply:

public class ExceptionAssertions {
    public static void assertException(BlastContainer blastContainer ) {
        boolean caughtException = false;
        try {
            blastContainer.test();
        } catch( Exception e ) {
            caughtException = true;
        }
        if( !caughtException ) {
            throw new AssertionFailedError("exception expected to be thrown, but was not");
        }
    }
    public static interface BlastContainer {
        public void test() throws Exception;
    }
}

Use it like this:

assertException(new BlastContainer() {
    @Override
    public void test() throws Exception {
        doSomethingThatShouldExceptHere();
    }
});

Zero dependencies: no need for mockito, no need powermock; and works just fine with final classes.