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

In JUnit 4 or later you can test the exceptions as follows

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

this provides a lot of features which can be used to improve our JUnit tests.
If you see the below example I am testing 3 things on the exception.

1. The Type of exception thrown
2. The exception Message
3. The cause of the exception

public class MyTest {

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

    ClassUnderTest classUnderTest;

    @Before
    public void setUp() throws Exception {
        classUnderTest = new ClassUnderTest();
    }

    @Test
    public void testAppleisSweetAndRed() throws Exception {

        exceptions.expect(Exception.class);
        exceptions.expectMessage("this is the exception message");
        exceptions.expectCause(Matchers.equalTo(exceptionCause));

        classUnderTest.methodUnderTest("param1", "param2");
    }

}