In addition to unit tests, Angular CLI also generates and configures e2e tests for your application. While unit tests focus on isolating the class-under-test, e2e tests are about integration testing. Angular CLI leverages Protractor along with WebDriver, so you can write automated acceptance tests (AAT) from the perspective of a user interacting with your application on a browser. As a rule of thumb, you should always write an order of magnitude more unit tests than AATs, because your app changes frequently and as a result, AATs are vastly more fragile and expensive to maintain compared to unit tests.
If the term web driver sounds familiar, it's because it is an evolution of the canonical Selenium WebDriver. As of March 30th, 2017, WebDriver has been proposed as an official web standard at the W3C. You read more about it at https://www.w3.org/TR/webdriver...
