[deleted]
For test automation, we built endpoints into the game client so we can interact with different aspects of the game. We have internal commands we can send to the game server to put ourselves in specific server states, and a verbose set of observable and control endpoints for different client states.
The back-end for the game is basically a cloud of clouds of services. The server teams write unit/component/integration tests for common regressions and high risk areas, but QAE focuses on testing the whole system rather than diving deep into component testing for individual APIs.