We don't have any tests for the $?LINE and $?FILE variables, although
they do work just fine as far as I can tell.
Here's a diff adding some in a new t/magical/vars.t file, since Autrijus
thought they should go in t/magical, but there doesn't appear to be a
good home for them there yet.
magical-vars.diff < 1K ]
--- t/magicals/vars.t (revision 0)
+++ t/magicals/vars.t (revision 0)
@@ -0,0 +1,10 @@
+is($?LINE, 9, '$?LINE works');
+is($?FILE, 't/magicals/vars.t', '$?FILE works');