Put it in a test script. Try it against edge cases (unusual test strings that might work when they shouldn't, or might not work when they should). For example:
use strict;
use warnings;
my @tests = (
".",
"",
"A sentence.",
".gitignore",
"word.doc",
"a.dotted.name",
);
print /^.*(\..*)$/ ? "Matched '$1' in " : "Failed", " '$_'\n" for @tes
+ts;
Prints:
Matched '.' in '.'
Failed ''
Matched '.' in 'A sentence.'
Matched '.gitignore' in '.gitignore'
Matched '.doc' in 'word.doc'
Matched '.name' in 'a.dotted.name'
Optimising for fewest key strokes only makes sense transmitting to Pluto or beyond