function __construct()
 {
     parent::__construct(__FILE__);
     // Remember this
     //creamos una categoria de test
     $this->load->model('category');
     $parent_id = NULL;
     $cat_attributes = array('name' => 'TEST_name', 'category_id' => $parent_id);
     Category::create($cat_attributes);
     $this->m_category = Category::find_by_id(Category::last()->id);
     $this->load->model('product');
     //buscamos cuantos productos hay de dicha categoria
     $this->m_category_products_count = Product::count_by_category_id($this->m_category->id);
 }