QMCDrivers/QMCOptimize, QMCCostFunction, etc. have no unit tests.

While in general the unit testing for QMCDrivers is quite poor it is not nonexistent and these drivers and support classes must gain unit tests if they are going to be part of the production code.

Unit tests define expected behavior for functions and methods while indicating dependencies via objects that must be mocked in order to test. If the tests are too "difficult" to write then clear problems of design exist.