如何在执行任何XCTest之前运行一次性的设置代码

I have the following problem. I want to execute a piece of code before all test classes are executed. For instance: I don't want my game to use the SoundEngine singleton during executing, but the SilentSoundEngine. I would like to activate the SilentSoundEngine one time not in all tests. All my tests look like this:I have the following problem. I want to execute