Android Studio creates a test folder, why?

Question

Android studio creates a test folder called androidTest with an ApplicationTest.java file by default upon creating a new project. It's obviously used for testing, but what kind of testing? In what circumstances should I use the test folder when developing an Android app?

Answer 1

but what kind of testing

The instrumentation testing that centers around the technologies in the Testing Support Library (e.g., Espresso, UI Automator).

Answer 2

You can do Android Instumentation Tests, or regular Junit4 testing. I recommend you do some kind of testing, if only to prevent regression of bugs. I favor test driven development (TDD), cf http://blog.pivotal.io/labs/labs/tdd-android-pov