TestNG: How to test for mandatory exceptions?

@Test(expectedExceptions) is useful for the most common cases:

• You expect a specific exception to be thrown
• You need the message of that exception to contain specific words

Per the documentation a test will fail if no expectedException is thrown:

The list of exceptions that a test method is expected to throw. If no exception or a different than one on this list is thrown, this test will be marked a failure.

Here are a few scenarios where @Test(expectedExceptions) is not sufficient:

• Your test method has several statements and only one of them is expected to throw
• You are throwing your own type of exception and you need to make sure it matches a certain criterion

In such cases, you should just revert to the traditional (pre-TestNG) pattern:

try {
  // your statement expected to throw
  fail();
}
catch(<the expected exception>) {
  // pass
}

Use @Test annotation to check expected exceptions.

@Test(
    expectedExceptions = AnyClassThatExtendsException.class,
    expectedExceptionsMessageRegExp = "Exception message regexp"
)

Or if you don't want to check for exception message, only below is enough

@Test(expectedExceptions = AnyClassThatExtendsException.class)

In that way, you don't need to use ugly try catch block, just invoke you exception-thrower method inside the test.