What about a simple test case testing if it's called multiple times it always returns the object with the same ID? Or it's not necessary?

Good point. Also we'll need to reset the global instance before each test, I guess.

I suggest using get_global instead of get_global_configuration. Since the method serves as constructor for the Configuration class - including "configuration" in the method name seems redundant. Leaving it up to you.

I was ready to tell you that it's named that way because of JS crawlee, but there it's called getGlobalConfig. I'm lost 😄