validates an exception happened

Validate Exception

public static void testValidation() {
    Boolean threwException = false;
    try {
    // magical test method logic here 
    } catch (Exception e) {
        threwException = true;
        Boolean expectedExceptionThrown = (e.getMessage().contains(validationString)) ? true : false;
        system.AssertEquals(true, expectedExceptionThrown, e.getMessage());
    }
    system.assertEquals(true, threwException, 'No exception was thrown');
}