What is Espresso tool

Testing is very essential in delivering high-quality software. We test both the business logic and UI to build high-quality software.
Espresso is a great library for UI testing
Espresso helps to write automated test cases so that they can be run multiple times
When you are writing an android application, We can test the application manually by looking at the screen finding the input fields, action buttons but it is a tedious job and we may miss corner cases in it.
Having automated tests ensures that everytime we make changes for the application on new changes, We can just run the automated test cases to validate that everything is running as expected.