Worker engine should not be testing against LOG calls

[Joshua Harlow]

The worker engine right now has unittests that check whether LOG (warn, exception, error) functions are called and associates these calls with whether a test passes or fails. This binds unittests to logging in a very unnatural way; LOG calls are changed to easily and to often and should not be depended on for failing/passing unit tests. An alternate mechanism checking against exceptions being raised, functions being called (*or other*) would be much more appropriate.