Android Development with Kotlin

Annotating properties

Kotlin generates multiple JVM bytecode elements from a single property (private field, getter, and setter). Sometimes, the framework annotation processor or the reflection-based library requires a particular element to be defined as a public field. A good example of this behavior is the JUnit test framework. It requires rules to be provided through a test class field or a getter method. We may encounter this problem when defining ActivityTestRule or Mockito's (mocking framework for unit tests) Rule annotation:

    @Rule 
    val activityRule = ActivityTestRule(MainActivity::class.Java) 

The preceding code annotates the Kotlin property that JUnit won't recognize, so ActivityTestRule can't be properly initialized. The JUnit annotation ...