Testing is crucial to e-commerce because e-commerce sites are both business critical and highly visible to their users; any failure can be immediately expensive in terms of lost revenue and even more expensive in the longer term if disaffected users seek alternative sites. Yet the time pressures in the e-commerce world militate against the thorough testing usually associated with business criticality, so a new approach is needed to enable testing to be integrated into the development process and to ensure that testing does not present a significant time burden.