[homarp]

https://docs.unrealengine.com/en-US/TestingAndOptimization/A... is the overview of the automation system used for unit testing, feature testing, and content stress testing.

[ensiferum]

There's some built-in testing functionality for the games but there aren't much tests for the engine itself in the source package.

Oh and I spent about 3 years working with UE4. The engine is a bug fest.