REGEX is a great feature of BASH, but in this case it was energy
needlessly spent. A `case` statement suffices. Bring in REGEX when
you're going to make good use of it, otherwise it's just going to bog
down your code.
I also wanted to strip the ` || exit 1` on the last line, but I wasn't
sure if this file is meant to be sourced or not; if not, then exiting
like that is redundant because it will already exit with whichever
status the last command provides, unless `popd` specifically offers
unhelpful or no exit statuses.
The tests are failing because $1 is being passed through from the
initial loading. When this loads in the shell, $1 is empty though so
the code works-for-me, but just not the tests.
This filters the $1 input to ensure its one of the valid types
expected inside the ./enabled directory.