use strict;
use warnings;
use Benchmark qw(cmpthese);
use File::Slurp;

my $TESTFILE = "foo";

die "'$TESTFILE' exists" if -e $TESTFILE;

sub slurp {
    local (@ARGV, $/) = $_[0];
    <>
}

for my $size (500, 5_000, 50_000, 500_000, 5_000_000, 25_000_000) {
    print "--- Test size: $size\n";

    open my $out, ">", $TESTFILE;
    print $out "x"x$size;
    close $out;

    cmpthese(-2, { fs_sub   => sub { my $x = read_file $TESTFILE },
                   is_sub   => sub { my $x = slurp $TESTFILE },
                   is_nosub => sub { my $x = do { local (@ARGV, $/) =
                                                  $TESTFILE; <> }; },
                 });

    unlink $TESTFILE;
}