There are a few mocking distributions on the CPAN, but I'll show an example using my Mock::Sub. You can mock out subs, then tell it to do something (side_effect()), or return something (return_value()). Instead of using a method to set them, you can also specify them in the constructor if you choose (then remove/modify them with the methods later):

use warnings;
use strict;

use lib '.';

use Mock::Sub;
use Test::More;
use Utils::Ldap::CompanyLdap;

my $m = Mock::Sub->new;
my $ldap = Utils::Ldap::CompanyLdap->new;

my $mocked_sub = $m->mock(
    'Utils::Ldap::CompanyLdap::searchGetEntries'
);
$mocked_sub->return_value(qw(steve mike dave));

read_users();

is $mocked_sub->called, 1, "searchGetEntries() called ok";

sub read_users { 
    for my $entry ($ldap->searchGetEntries()){
        print "$entry\n";
    }
}

done_testing();
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Output:

steve
mike
dave
ok 1 - searchGetEntries() called ok
1..1
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