Testing for exceptions in JUnit is something we have to deal with! We want to test if an exception occurs in a particular situation, or even if the exception contains a particular message. The question is: How to test for an exception in Junit? What we see very often is this:

import org.junit.Test;

public class JDrivenServiceTest {

    JDrivenService service = new JDrivenService();

    @Test(expected = ArticleNotFoundException.class)
    public void testPublishArticle_WithException() throws Exception {
        service.publishArticle(null);
    }
}

Or this, which is worse in my opinion:

import org.junit.Test;

import static org.junit.Assert.fail;

public class JDrivenServiceTest {

    JDrivenService service = new JDrivenService();

    @Test
    public void testPublishArticle_WithException() throws Exception {
        try {
            service.publishArticle(null);
            fail();
        } catch (ArticleNotFoundException e) {
            //Do some Asserts here.
        }
    }
}

What would be much better is to use the @Rule Annotation in combination with the ExpectedException class like this:

import org.junit.Test;

import org.junit.Rule;
import org.junit.rules.ExpectedException;

public class JDrivenServiceTest {

    @Rule
    public ExpectedException thrown = ExpectedException.none();

    JDrivenService service = new JDrivenService();

    @Test
    public void testPublishArticle_WithException() throws Exception {
        thrown.expect(ArticleNotFoundException.class);
        thrown.expectMessage("Article not found");
        thrown.expectMessage("please provide an article to publish");

        service.publishArticle(null);
    }
}