I tried this. Look in the home directory afterwards for "K":

#!/usr/bin/perl

use strict;
use warnings;
use FileHandle;
use File::Tee qw(tee);
use Test::MockObject::Extends;

tee('STDOUT', '>>', 'stdout.txt');

my $mock= Test::MockObject::Extends->new(FileHandle->new);
$mock->set_false( 'print' );
$mock->mock('FileHandle');

my $a = FileHandle->new;
die "could not open" unless $a->open('>K');
die "I expect to die here" unless print {$a;} "hello";
die "I expect to be dead before we get to this point" 
unless $a->print("hello");
print $a;
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