Companion object in Kotlin

Question

Companion object in Kotlin

Just switching from Java to Kotlin. There was a question, the answer to which, unfortunately, I could not find. There is an abstract class with several abstract variables, which will then be subjected to dozens of tests. Testing with JUnit. The annotated @BeforeClass and @AfterClass methods are required to be static, and I see only one way to resolve the whitespace: push the methods inside companion object, where you can use @JvmStatic, but at the same time, the @BeforeClass method calls the abstract a variable that is set by each implementation separately. Accordingly, how can I access a variable from an external class? Or maybe there is another way to solve such a problem? Code:

abstract class TemplateConfig {

    abstract val template : String?


    companion object {
        lateinit var h: Handle

        @BeforeClass
        @JvmStatic
        fun setUp() {
            h = dbi.value.open()
            //Здесь используется абстрактная переменная
            //
            //if (template != null) {
            //    h.createStatement(template).execute()
            //}
        }

        @AfterClass
        @JvmStatic
        fun tearDown() {
            h.close()
        }

        //{...Объявление и инициализация других переменных...}
    }
}

3

kotlin тестирование junit

Author: Янислав Корнев, 2016-08-19

Source

1 answers

score 1 · Accepted Answer

If I understand correctly, you are trying in a static method to refer to a non-static variable / method that is set in the descendant class. It won't work that way. The only solution I can see is to define the field as static and, when initializing the descendant class, set it to a value.

object Demo {
   protected var value:String
   @BeforeClass
   fun setUp() {
      println(value)
   }
   @AfterClass
   fun destroy() {
   }
}
internal class SubClass:Demo() {
   companion object {
     init {
        Demo.value = "this is value"
     }
   }
}