The GUI example: 1) Make the webdriver based test click a button which does not exists yet. The test will fail, you know that there is no other button which by

The GUI example: 1) Make the webdriver based test click a button which does not exists yet. The test will fail, you know that there is no other button which by chance matches this selector. 2) Add the button to the app, the test turns green, 3) you Continue to extend the test to click another botton, etc till it fails again The Game example: e2e tests for games probably do not make much sense (I've no experience here). So you will have components/unit tests. Those have a defined interface and behaviour. You want to change this, you change the test first like in any other project. The Audio engine - what is an audio engine?