Testing the UI

Now that we have the mechanisms to test our application logic, and at the same time we're sure nothing was broken when we added new functionality or modified the already existing features, we could add some more tests to check whether the UI behaves as it should.

Writing UI tests with the Espresso framework is quite similar to writing plain instrumentation tests; the difference is in navigating and performing checks and actions on UI views and the elements on the screen. When a UI test is executed, the emulator or real Android device will show the changes and actions in real time as if somebody was triggering those actions.

Setup

To set up the Espresso framework, we will not require additional work if we have configured our project for instrumentation tests already. We have to be sure that our build.gradle file contains the Espresso dependencies:

androidTestCompile 'com.android.support.test.espresso:espresso-core:2.2.2' 
androidTestCompile 'com.android.support.test:runner...