Eliminate needless test boilerplate, and duplicated effort.

Eliminate needless test boilerplate, and duplicated effort.

There's no need to change directory or duplicate the effects of -Mblib.
Let use do the importing, rather than an explicit import call.
use_ok() is arguably harmful - just let the use fail and take the entire test
out cleanly, rather than carrying on and generating meaningless failures.
No need to test ->can() and $VERSION in both - once is sufficient.