PDF::PDFUnit let's us verify PDF documents using perl. It seems to do a good job, except for the notContaining function. It seems to always return true (here a rewritten version of 01-load.t). The basic idea is to detect presence of unwanted words, such as the name of the former CEO:

$ cat t/01-test-mod.t 
use strict;
use utf8;
use warnings;
use FindBin;
use File::Spec;

use Test::More;
use Test::Exception;
use PDF::PDFUnit qw(:skip_on_error);

my $resources_dir = File::Spec->catfile($FindBin::Bin, 'resources');
my $pdfReference = "$resources_dir/reference.pdf";

lives_ok {
    AssertThat
        ->document($pdfReference)
        ->hasText()
        ->containing("Hello")
} "containing Hello";

lives_ok {
    AssertThat
        ->document($pdfReference)
        ->hasText()
        ->notContaining("Hello")
} "notContaining Hello";

diag $@->getMessage() if $@;
done_testing();

__END__
$ perl t/01-test-mod.t 
ok 1 - containing Hello
ok 2 - notContaining Hello
1..2
$
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openjdk-8-jre:amd64 + Ubuntu 16.04.1 LTS + perl v5.22.1

BR
Andreas