I'm trying to add a line on invoices before delivery orders lines, but it seems my code it's not executed, i tryed this to test:

from openerp.osv import fields, osv

class sale_order_line(osv.osv):

    _inherit = "sale.order.line"

    def invoice_line_create(self, cr, uid, ids, context=None):

        res = super(sale_order_line,self).invoice_line_create(cr, uid, ids, context=None)
        vals = {
            'name': test,
            'account_id': 1094,
            'price_unit': 0,
            'quantity':0,
         }
         inv_id = self.pool.get('account.invoice.line').create(cr, uid, vals, context=context)
         self.write(cr, uid, 0, {'invoice_lines': [(4, inv_id)]}, context=context)
         sales.add(0)
         create_ids.append(inv_id)
         return res

This code seems to do nothing. It could be an inherit problem or super is overwrtitting the result?.

EDITED ON 23/10/15

I had also tested this code, and messagebox it's not shown:

from openerp.osv import fields, osv

class sale_order_line(osv.osv):
    _name = 'sale.order.line'
    _inherit = 'sale.order.line'

    def invoice_line_create(self, cr, uid, ids, context=None):

        res = super(sale_order_line, self).invoice_line_create(cr, uid, ids, context=context)
        raise osv.except_osv(_('Test'), _('This is a test'))
        return res