Cannot test a class that return a customException

Question

While experimenting JUnit, I am trying to test a simple private method as follows, this method receives a String and make sure it does not include the word \'Dummy\' in it.

Answer 1

I agree with @Stultuske in the comments above and would rewrite the test to:

@Test
public void shouldThrowExceptionForInvalidString() {

    try {
        MyClass myCls = new MyClass();
        Method valStr = myCls.getClass().getDeclaredMethod(
                "validateString", String.class);
        valStr.setAccessible(true);
        valStr.invoke(myCls, "This is theDummyWord find it if you can.");
    } catch (Exception e) {
        assert(e instanceOf CustomException);
        assert(e.getMessage.equals("String has the invalid word!"));
    }

}

Or if you want to use ExpectedException

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

@Test
public void shouldThrowExceptionForInvalidString() {

    thrown.expect(CustomException.class);
    thrown.expectMessage("String has the invalid word!");

    MyClass myCls = new MyClass();
    Method valStr = myCls.getClass().getDeclaredMethod("validateString", String.class);
    valStr.setAccessible(true);
    valStr.invoke(myCls, "This is theDummyWord find it if you can.");

}