sub big_one {
    # a lot of code here
    my ($foo, $bar, $quux);
    {
         # Big block of code nobody had courage to move into a subroutine
    };

    refute_these {
        can_ok $foo, qw(so_this frobnicate), "Assigned an object to foo";
        like $bar, qr/f?o?r?m?a?t?/, "bar is in right format";
        is_deeply $quux->{megahash}, $_[0]->{megahash}, "Data round-trip"; 
    };

    # even more code

}; # sub ends some 500 lines below