[Lorkki]

> Unity games are usually written in C#

That is true in the most literal sense, but Unity have adopted a programming model that makes much of the normal tooling around .NET useless, and abhors automated testing.

Adopting good testing practices in Unity still largely revolves around developing parts of your game as .NET libraries that get tested before being built and integrated into the game, and it's not too surprising that many developers don't go down this route.