Hoge.pm

package Hoge;
use strict;
use warnings;
use utf8;

use MyCon;

sub hage {
    HOGE;
}

1;

MyCon.pm

package MyCon;
use strict;
use warnings;
use utf8;

use Const::Common (
    HOGE => 'はげ',
);

1;

test.t

use strict;
use warnings;
use utf8;
use Test::More;
use Hoge;
use Test::Mock::Guard;

subtest 'orig' => sub {
    is Hoge::hage, 'はげ';
};

subtest 'hagemaru' => sub {
    my $g = mock_guard Hoge => {
        hage => 'ハゲマル',
    };
    is Hoge::hage, 'ハゲマル';
};

done_testing;