What is an Android testing framework?

One of the most standard testing frameworks for Android applications is the Android testing framework. It is comprised of three segments:

• Application Package
  It is the target application which requires to be tested.
• Instrumentation Test Runner
  This part of the framework serves as a Test Case Runner, allowing test cases to run on the target application. It includes two parts: an SDK tool for building test; and a tool that provides APIs for writing program which controls an Android device or an emulator outside of Android codes (i.e., MonkeyRunner)
• Test Package
  It consists of two components: Test case classes and Mock objects. Test case classes constitute test methods to perform the on-target application, while mock objects include mock data used as sample input for test cases.