Don’t require developers to modify their apps in any way just to start using your test library. Developers should be able to test their app “as-is.” There are several reasons this is important — some technical, others cultural. Developers want to keep the surface area of their apps as small as possible. Having extra code lying around in the app leads to an unnecessary increase in file size and another potential vector for bugs or security holes. And some teams charged with test automation are separated from the developers who compiled the app. They have to write tests, but they might not have any (or at least, an easy) way to modify the source just to make it automatable. Yes, that’s sad and wrong, but a reality for many organizations. The least you can do is make their lives a little more comfortable. Make it easy to test an app as-is.