Best way to check whether a certain exception type was the cause (of a cause, etc ...) in a nested exception?

Question

I am writing some JUnit tests that verify that an exception of type MyCustomException is thrown. However, this exception is wrapped in other exceptions a number of times, e.g. in an InvocationTargetException, which in turn is wrapped in a RuntimeException.

What's the best way to determine whether MyCustomException somehow caused the exception that I actually catch? I would like to do something like this (see underlined):

 try {     doSomethingPotentiallyExceptional();     fail("Expected an exception."); } catch (RuntimeException e) {      if (!e.wasCausedBy(MyCustomException.class)         fail("Expected a different kind of exception."); } 

I would like to avoid calling getCause() a few "layers" deep, and similar ugly work-arounds. Is there a nicer way?

(Apparently, Spring has NestedRuntimeException.contains(Class), which does what I want - but I'm not using Spring.)

CLOSED: OK, I guess there's really no getting around a utility method :-) Thanks to everybody who replied!

Answer 1

If you are using Apache Commons Lang, then you can use the following:

(1) When the cause should be exactly of the specified type

if (ExceptionUtils.indexOfThrowable(exception, ExpectedException.class) != -1) {     // exception is or has a cause of type ExpectedException.class } 

(2) When the cause should be either of the specified type or its subclass type

if (ExceptionUtils.indexOfType(exception, ExpectedException.class) != -1) {     // exception is or has a cause of type ExpectedException.class or its subclass }