Unit tests in D

[bearophile]

Leandro Lucarella:
> Please, remove the leading __ from features that are standard (as oposed
> from implementation extensions). 

I appreciate Walter's decision to use those __names: it allows us to use and try a feature now, it allows to create its implementation progressively, and gives time to design its user interface well after it's being used for some time.

Bye,
bearophile