In order to test the high level of our application's code and to create system tests, we will write tests that work with browsers, and verify that the UI code is functioning properly. Using a tool called Selenium, we will create Python code that hooks into a browser and controls it purely from code. This works by finding elements on the screen, and then performing actions on those elements through Selenium. Click on it or input keystrokes. Also, Selenium allows you to perform checks on the page content by giving you access to the elements' content, such as their attributes and inner text. For more advanced checks, Selenium even has an interface which can run arbitrary JavaScript on the page. If the JavaScript returns a value, it is automatically converted into a Python type.

Before we touch the code, Selenium needs to be installed. Make sure you...