This is, afaict, a completely backwards compatible way to add this
functionality in the sense that any of the non-error command-line
arguments passed to raco test before still do precisely the same
things
original commit: 9fd4698be9
This convention makes it easier to deal with a set
of ".rkt" files that implement tests, while a `test'
module implements a `main'-like split for some of the
files.
original commit: 63a4414863
