Espresso is a testing framework for Android that allows developers to write automated tests for their applications. The benefit of automated testing is that you can write a test plan, and simply hit run and have all of the important features in your app tested effortlessly, and arguably more consistent and thorough than manual testing. There is no doubt that it is a lot faster.

However, one of the lesser known development patterns for automated testing is the robot pattern, which makes writing tests much easier while providing a painless way to update tests whenever your app changes. Let’s take a deeper dive into what makes the robot pattern so powerful, and how to implement it in your next test suite.

Every Java programmer has faced the dreaded NullPointerException at some point in their life. Sometimes it’s your fault, sometimes it’s a pesky race condition. Regardless, it’s a head ache and generally leads to a ton of if (myVariable != null) { } conditions all over your code. However, the latest craze Kotlin can help with that too. Kotlin introduced null safety into its type system, with the potential of removing all NPEs.

This post is both going to review the official docs linked above, as well as provide some common tips and tricks to work with the nullability - something that is new in this language for many Java programmers.

This year at Google I/O, the Android team announced Android Architecture Components a combination of new, helpful libraries for Android development. One that particularly interested me was the Room Persistence Library, which is an abstraction layer of SQLite designed to make database access and creation a lot easier. Right off the bat it reminded me of Realm, which I learned about at Droidcon NYC and really admired, so I decided to dive in and build a todo list using Room & RxJava.

If you’ve been following along with parts 1-3, you now have an (almost) working todo list application. The only thing we are missing is persisting the data. Running your Android app now and rotating your screen will show you that the items you add won’t persist, and disappear anytime an activity is killed and recreated. This post will show you how to write the list to a text file and read from it.

Following parts 1 and 2 you should have a working Android app in Kotlin that displays a list of Tasks to be completed and lets you mark them as complete. This segment is going to show you how to implement support for adding new items.