One more very simple way to do this that I regularly use is to install a bunch of Perl versions using perlbrew and then run a simple test using e.g. perlbrew exec perl -wMstrict -e 'my $x="foobar"; $x=~s/^foo\Kbar$/x/; die unless $x eq "foox"'. This will allow you to very quickly test how code behaves on different Perl releases. (If you wanted to dig much deeper for the development history, you could bisect the source code.)