feat(developer): add unit tests for meta compiler

First, a little bit of refactoring to make it cleaner to do unit test
for each section.

Then add some global error values.

Throw in a helper function or two.

Dust off the edges of the CompilerCallbacks object.

Duct tape together validation of the normalization attribute.

And ... eventually we get a nice clean-like unit test for the meta
compiler, with three pretty little fixtures and as-neat-as-you-like-it
assertions.