@Test
public void throwsUnhandledExceptionWithCauseOfInternalExceptionWhenExceptionMapperForCauseIsNotAvailable() throws Exception {

    Exception exception = new Exception();
    InternalException internalException = new InternalException(exception);
    doThrow(internalException).when(requestDispatcher).dispatch(request, response);
    when(providers.getExceptionMapper(Exception.class)).thenReturn(null);
    thrown.expect(UnhandledException.class);
    thrown.expectCause(exceptionSameInstanceMatcher(exception));
    requestHandler.handleRequest(request, response);
}