For a while now, Agile development has been problematic for Android developers. There have been a number of ways to test the user interface (UI), such as Robotium or Monkey Runner, but before Android Studio 1.1, unit testing was hard to use, hard to configure, and quite challenging to implement on the Android platform.
Google would argue, no doubt, that in the past you could use JUnit3-style unit testing. But for anyone from classic Java development this was a dramatic backward step in time. Developers would stumble along hacking together a JUnit4 development environment using a number of third-party tools. More likely than not they would simply give up as the ever-increasing series of mutually incompatible library ...