This is a configuration that is expected to validate, and to exercise
as much as possible of the code up until validation has
completed. That is, as much as possible of the configuration
validation code.
It currently instantiates all modules, but not yet all particles and
decorations.
Initial set of tests verifying we fail when trying to load:
a) a non-existing configuration
b) a non-regular file configuration (e.g. a directory)
c) configuration exists, but has no top-level 'bar' entry
