A big cost area in testing is manual user interface testing. Therefore, a wide range of tools has been developed to automate running tests at the HTTP level. Selenium is a popular tool implemented in Java, for example. In the Node.js world, we have a few interesting choices. The chai-http plugin to Chai would let us interact at the HTTP level with the Notes application while staying within the now-familiar Chai environment.
However, in this section, we'll use Puppeteer (https://github.com/GoogleChrome/puppeteer). This tool is a high-level Node.js module used to control a headless Chrome or Chromium browser, using the DevTools protocol. This protocol allows tools to instrument, inspect, debug, and profile Chromium or Chrome browser instances. The key result is that we can test the Notes application in a real browser so that we have greater assurance it behaves correctly for users.
