Here is the Boost Test assertion:

    BOOST_CHECK_EXCEPTION(dummyOpr->setOperand(emptyValue), DiGSE::fail, fail_msg);

Here is the test execution log message:

    info: check 'incorrect exception DiGSE::fail is caught' has passed

I have only one exception:  DiGSE::fail (derived from std::exception).  It is the only exception that appears in the BOOST_CHECK_EXCEPTION() assertions.  So, what does "incorrect exception DiGSE::fail" mean?  If DiGSE::fail was caught, then that part is correct.  If the message means that some other exception was caught, then this is a Really Poor way of phrasing that information.

Or, did the predicate return false (which, in my case, means the exception message is wrong)?

But if the wrong exception was caught or the predicate returned false, then why was the assertion declared "has passed"?

Merrill Cornish