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

Answer 1

Why would you want to avoid getCause. You can, of course, write yourself a method to perform the task, something like:

public static boolean isCause(
    Class<? extends Throwable> expected,
    Throwable exc
) {
   return expected.isInstance(exc) || (
       exc != null && isCause(expected, exc.getCause())
   );
}

Answer 2

Based on Patrick Boos answer: If you using Apache Commons Lang 3 you can check:

indexOfThrowable: Returns the (zero based) index of the first Throwable that matches the specified class (exactly) in the exception chain. Subclasses of the specified class do not match

if (ExceptionUtils.indexOfThrowable(e, clazz) != -1) {
    // your code
}

or

indexOfType: Returns the (zero based) index of the first Throwable that matches the specified class or subclass in the exception chain. Subclasses of the specified class do match

if (ExceptionUtils.indexOfType(e, clazz) != -1) {
    // your code
}

Example for multiple types with Java 8:

Class<? extends Throwable>[] classes = {...}
boolean match = Arrays.stream(classes)
            .anyMatch(clazz -> ExceptionUtils.indexOfType(e, clazz) != -1);