I tried this on NT Emacs (although with a different language) using a utf8 source file:

  use utf8;
  use Test::Simple tests=>1;

  use strict;

  sub трщь {
    return 1;
  }

  ok( трщь(), "Unicode Sub" );

The result was:

C:\temp>perl -w russian.pl
1..1
ok 1 - Unicode Sub
[download]

on Windows 2000.