The quick answer is “all kinds”, but QA usually has a collection of [test plans] that provide a road map for QA to validate specific content, systems, or features. A test plan is a list of specific tests they run in order to make sure that a specific chunk of the game is functioning as expected. This test plan might be (broadly) to make sure each of the class abilities meets expectations, or to cover all of the level geometry and object placement in the sewer dungeon, or to check that the game meets all of the known platform certification requirements. The totality of all of these test plans together should encompass testing the entire game.
These test plans come from a variety of sources. Certification requirements are obtained from platform and past failed certification submission notes. Game system test plans are written by the designers who created the rules for the game system. Level design test plans are usually written by the level designers who create the levels. There’s also tech test plans where an engineer could write a list of tests for graphics settings or online matchmaking. Whenever a specific test is failed and the tester observes unexpected behavior, they create and log a new bug.
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