The Incredible Journey

Here is the coverage of Faster.xs in the module Gzip::Faster:

http://cpancover.com/latest/Gzip-Faster-0.21/Faster-xs--branch.html

It suggests that most of these statements aren't tested. But actually they are, more or less.

What seems to be happening is that SvTRUE is a macro with about five or six different tests:

https://github.com/Perl/perl5/blob/blead/sv.h#L1761

and so to get "coverage" of all the SvTRUEs here I'd need to send a string, an integer, a floating-point number, and so on and so on. But would that actually tell anything about Gzip::Faster? In fact it wouldn't. It would just be testing whether SvTRUE from Perl's core was working correctly or not.