How to test for the exception in junit

Question

Let's say I have my method myMethod checking a series of scenarios then throws exception accordingly without handling those exceptions.

public MyResponse myMethod(MyRequest req)
{
    try
       {
          if(req.property1 == null || req.property1.isEmpty())
             throw new Exception("Property 1 is null of empty");

          if(req.property2 == null || req.property2.isEmpty())
             throw new Exception("Property 2 is null of empty");

          //if no problem is found then proceed ...
       }
       catch(Exception e)
       {
          //log error
          throw e;
       }

}

How do I test the exception being thrown or at least check the message that was sent with the exception?

@Test
public void aNullOrEmptyProperty1CausesExceptionTest() throws Exception {
    //..
    String property1 = "";
    req.setProperty1(property1);
    //...
    MyResponse response = target.myMethod(req);

    //How to check for the exception?
}

Thanks for helpin

In the same way that you did inside `myMethod`, you will want to `catch` it. — Spencer Wieczorek, Feb 09 '18 at 16:26

score 3 · Accepted Answer · answered Feb 09 '18 at 16:33

3

I don't know if it's available in all versions of JUnit (I use junit 4.12). What I usely do is to add the expected exception after the Test annotation, for example:

@Test(expected = MySpecificException.class)

There are other ways to do, but that's a possibility. You can create a specific MySpecificException class (which extends Exception class), and you throw this specific exception in your code. Then you can check that it is thrown correctly with junit.

Have fun !

answered Feb 09 '18 at 16:33

E. Bavoux

535
1
4
11

See the linked duplicate answer for why this isn't always effective. – Andrew S Feb 09 '18 at 17:00
It's working. What if you want to access the exception object and read the message that was sent? – Richard77 Feb 10 '18 at 22:41

How to test for the exception in junit

1 Answers1