Integrating Codeception testing

How do you get around the issue with helpers when running the test? I keep getting the following errors when I run them via codeception...

Code:

PHP Fatal error:  Call to a member function is_mobile() on a non-object in /var/www/dev/application/helpers/MY_html_helper.php on line 58



<? function select_image($trigger, $target) { ?>
    <? $target = str_replace('#', '', $target) ?>
    <a href="/photo_selector?target_id=
A PHP Error was encountered

Severity: NoticeMessage:  Undefined variable: targetFilename: /var/www/dev/application/helpers/image_helper.phpLine Number: 3