Idea: test script to run after local luarocks install

[mrcjkb]

luarocks test/busted uses the source directories (defined in lpath of the .busted file) to run tests, not the luarocks package as defined in the rockspec.

It would be nice to have a way to run some tests against the installed package, to validate that the package works as expected.

For this purpose, a simple validate-install-cmd input may suffice.
It could be something like:

with:
  validate-install-cmd: |
    nvim -c <load-installed-package> -l require('my-package').setup()