module tests

[domenkozar]

We could add module tests declaratively like this:

{ pkgs, ... }: {

  tests.foo  = {
   nix = ''{ pkgs, ... }: {}'';
   yaml = "...";
   test = ''
   '';
  };
}

And then have a devenv test that collects and runs them.

[domenkozar]

Note that there should also be a way to test the devenv, by running a script and devenv up. There's quite some overlap here.

EDIT: probably we should just start devenv up if any processes are defined.