/**
 * Return a custom field value.
 *
 * @param  string  $name    Option name
 * @param  integer $post_id Post ID
 * @param  mixed   $default Default value
 *
 * @return mixed            Meta value
 * @since  3.0.0
 */
function wpas_get_cf_value($name, $post_id, $default = false)
{
    $field = new WPAS_Custom_Field($name);
    return $field->get_field_value($default, $post_id);
}
 public function test_get_field_value()
 {
     update_post_meta($this->ticket_id, '_wpas_my_test_field', 'hello');
     $this->assertEquals('hello', $this->text_field->get_field_value('', $this->ticket_id));
     $this->assertEquals('hello', wpas_get_cf_value('my_test_field', $this->ticket_id, ''));
 }