Others have pointed out that C++ is a necessity for at least the high-end games that push the hardware. High-level languages are used for scripting and logic (especially Lua). Deploy-measure-iterate is often used in the after-market for those games where it is appropriate, and in-house before release.

However I've never heard of TDD being used. Also C++ tends to be used as the proverbial hammer (e.g. for scanning debug output, build scripts). C# is quickly taking over for tools but it's also taking over as the new improved hammer.