source: vendor/perl/5.8.8/lib/IPC/Open3.t

#!./perl -w

BEGIN {
    chdir 't' if -d 't';
    @INC = '../lib';
    require Config; import Config;
    if (!$Config{'d_fork'}
       # open2/3 supported on win32 (but not Borland due to CRT bugs)
       && (($^O ne 'MSWin32' && $^O ne 'NetWare') || $Config{'cc'} =~ /^bcc/i))
    {
        print "1..0\n";
        exit 0;
    }
    # make warnings fatal
    $SIG{__WARN__} = sub { die @_ };
}

use strict;
use IO::Handle;
use IPC::Open3;
#require 'open3.pl'; use subs 'open3';

my $perl = $^X;

sub ok {
    my ($n, $result, $info) = @_;
    if ($result) {
        print "ok $n\n";
    }
    else {
        print "not ok $n\n";
        print "# $info\n" if $info;
    }
}

sub cmd_line {
        if ($^O eq 'MSWin32' || $^O eq 'NetWare') {
                my $cmd = shift;
                $cmd =~ tr/\r\n//d;
                $cmd =~ s/"/\\"/g;
                return qq/"$cmd"/;
        }
        else {
                return $_[0];
        }
}

my ($pid, $reaped_pid);
STDOUT->autoflush;
STDERR->autoflush;

print "1..22\n";

# basic
ok 1, $pid = open3 'WRITE', 'READ', 'ERROR', $perl, '-e', cmd_line(<<'EOF');
    $| = 1;
    print scalar <STDIN>;
    print STDERR "hi error\n";
EOF
ok 2, print WRITE "hi kid\n";
ok 3, <READ> =~ /^hi kid\r?\n$/;
ok 4, <ERROR> =~ /^hi error\r?\n$/;
ok 5, close(WRITE), $!;
ok 6, close(READ), $!;
ok 7, close(ERROR), $!;
$reaped_pid = waitpid $pid, 0;
ok 8, $reaped_pid == $pid, $reaped_pid;
ok 9, $? == 0, $?;

# read and error together, both named
$pid = open3 'WRITE', 'READ', 'READ', $perl, '-e', cmd_line(<<'EOF');
    $| = 1;
    print scalar <STDIN>;
    print STDERR scalar <STDIN>;
EOF
print WRITE "ok 10\n";
print scalar <READ>;
print WRITE "ok 11\n";
print scalar <READ>;
waitpid $pid, 0;

# read and error together, error empty
$pid = open3 'WRITE', 'READ', '', $perl, '-e', cmd_line(<<'EOF');
    $| = 1;
    print scalar <STDIN>;
    print STDERR scalar <STDIN>;
EOF
print WRITE "ok 12\n";
print scalar <READ>;
print WRITE "ok 13\n";
print scalar <READ>;
waitpid $pid, 0;

# dup writer
ok 14, pipe PIPE_READ, PIPE_WRITE;
$pid = open3 '<&PIPE_READ', 'READ', '',
                    $perl, '-e', cmd_line('print scalar <STDIN>');
close PIPE_READ;
print PIPE_WRITE "ok 15\n";
close PIPE_WRITE;
print scalar <READ>;
waitpid $pid, 0;

# dup reader
$pid = open3 'WRITE', '>&STDOUT', 'ERROR',
                    $perl, '-e', cmd_line('print scalar <STDIN>');
print WRITE "ok 16\n";
waitpid $pid, 0;

# dup error:  This particular case, duping stderr onto the existing
# stdout but putting stdout somewhere else, is a good case because it
# used not to work.
$pid = open3 'WRITE', 'READ', '>&STDOUT',
                    $perl, '-e', cmd_line('print STDERR scalar <STDIN>');
print WRITE "ok 17\n";
waitpid $pid, 0;

# dup reader and error together, both named
$pid = open3 'WRITE', '>&STDOUT', '>&STDOUT', $perl, '-e', cmd_line(<<'EOF');
    $| = 1;
    print STDOUT scalar <STDIN>;
    print STDERR scalar <STDIN>;
EOF
print WRITE "ok 18\n";
print WRITE "ok 19\n";
waitpid $pid, 0;

# dup reader and error together, error empty
$pid = open3 'WRITE', '>&STDOUT', '', $perl, '-e', cmd_line(<<'EOF');
    $| = 1;
    print STDOUT scalar <STDIN>;
    print STDERR scalar <STDIN>;
EOF
print WRITE "ok 20\n";
print WRITE "ok 21\n";
waitpid $pid, 0;

# command line in single parameter variant of open3
# for understanding of Config{'sh'} test see exec description in camel book
my $cmd = 'print(scalar(<STDIN>))';
$cmd = $Config{'sh'} =~ /sh/ ? "'$cmd'" : cmd_line($cmd);
eval{$pid = open3 'WRITE', '>&STDOUT', 'ERROR', "$perl -e " . $cmd; };
if ($@) {
        print "error $@\n";
        print "not ok 22\n";
}
else {
        print WRITE "ok 22\n";
        waitpid $pid, 0;
}