The *.input files for the tests are what we call "tags files". They are
generated by rpm2tags.

The tests:

- rpm.glib.input:

  Generated from glib2-2.46.2-4.el7.i686.rpm (downloadable from
  rpmfind.net).

- rpm.custom.input:

  Generated from our own custom package (see test.spec in this
  distribution). The advantage of this custom package is that it lets us
  test the helper with almost all the tags it's supposed to support.

--

The way we test this helper is a bit unconventional:

We aren't overriding one or two variables in the helper but, instead,
inject a code snippet into it (see 'rpm.rewrite.sh'). This lets us
override a couple of functions to imitate the 'rpm' binary.