Test tool independence occurs when the test suite is not heavily integrated with any given testing tool. For example, switching from Selenium 1 to Selenium WebDriver is difficult, because both tools use different methods to locate and click on page elements. If we wrote our framework in such a way as to hide these changing methods from the test, all we need to do to upgrade to Selenium WebDriver is update the find_element and click methods to use the new WebDriver API. This practice is referred to as the Adapter pattern. In the previous example of this chapter, the SidebarCart class acts as an adapter between the test and the instance of Selenium WebDriver by translating the add_to_cart method call into a WebDriver click method.