Every game company that I have applied to that has given a programming test, has done the test in C++. The school I went to used C++ as the language. I have only used C# on business applications, enterprise web applications and the few Unity projects I’ve worked on. The games I’ve worked on have always been C or C++ for the engine, and then with a scripting language on top such as python, lua or UnrealScript.
Unity is a C++ application. All the people that whine about C++ being too hard and saying Unity does it right seem to forget that Unity is a C++ app that doesn’t give access to the average developer of the code, so you are very much just an end user.