nosepass / todo_notifier

Todo Notifier

This is mainly an example of unit and integration testing an MVP android app that uses Kotlin, Dagger 2, Rx, and Cupboard. The app itself shows a nagger in the Android notification bar every X minutes, where X is a setting stored in SQLite. I chose SQLite instead of SharedPreferences solely so I could play around with asynchronus apis.

##Setup Aside from what build.gradle has taken care of, you need two Kotlin plugins in Android Studio, "Kotlin" and "Kotlin Extensions for Android". I am using Android Studio 1.2 for the unit testing support.

##Quick Android Testing Refresher There are a few types of tests Google suggests you use in Android. You can write jvm unit tests, instrumented "unit" tests, and instrumented integration tests. Plain jvm unit tests live in src/test, instrumented tests that run on a device live in src/androidTest. In Android Studio, you can only use one test type at a time, switching between "Unit Tests" and "Android Instrumentation Tests" in the Build Variants view as needed. This projects uses both types.

##Challenges ###Kotlin

• Dagger modules and component classes must be Java, since that part of the Dagger annotation processing runs before Kotlin classes are compiled. Parts of Application had to be in Java as well, since Dagger initialization also needed to be in Java.
• Dagger cannot access Kotlin fields, so you have to create and annotate setters with @Inject to allow Dagger to inject into Kotlin objects.
• Using @Named Dagger dependencies needed a more verbose setter variation, with @Named being on the parameter of the setter.
• Kotlin cannot be used for unit tests, the test runner can't see the classes created by kotlin-gradle for some reason. Integration tests can be in Kotlin, but AS does not create run configurations for them automatically.
• Static initializers do not exist in Kotlin, and were the suggested way to configure Cupboard. I had to use an alternate method of registering model classes for Cupboard.
• Mocking Kotlin classes with Mockito doesn't work right. When you call when(mock(SomeOpenKotlin.class)).someMethod(), Mockito is supposed to prevent the invocation of someMethod and just use it to declare mocking behavior. However the kotlin implementation of the someMethod always gets called for some reason. A workaround is to define an interface/trait and mock that instead of the concrete implementation. Strangely enough, when an interface is available, you are able to mock the concrete class as well.

###Structuring Dagger for mocking With Dagger 2 you have to create alternate components and modules for testing, since you can't extend and override the behavior of your original modules. These were was placed in src/debug for use by both the unit and instrumentation tests. However you need to maintain the debug versions in lockstep with the originals.

Unit Testing

I decided to not use the unitTests.returnDefaultValues flag in my build.gradle. This forces me to mock any Android classes I use, lest they throw a RuntimeException. I was taken by surprise when libraries such as RxAndroid used the Android api indirectly and in a difficult to mock way, such as the AndroidSchedulers class.

Google's Integration Test Changes

Instead of using ActivityInstrumentationTestCase2, I am following this: https://code.google.com/p/android-test-kit/wiki/JUnit4RulesInATSL