SubClass.java

package entities;

public class SubClass extends SuperClass {
    private int attribute;

    public int getAttribute() {
        return attribute;
    }
}

SuperClass.java

package entities;

import java.lang.reflect.Field;

public class SuperClass {


    public void __set(String field, Object value){
        try {
            Field f = getClass().getDeclaredField(field);
            f.setAccessible(true);
            f.set(this, value);
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
    }
}

Test.scala

import entities.SubClass
import org.specs2.mutable._

class ReflectionClass extends Specification{

  "Uma classe com estado" should {
    "poder definir um estado " in {
      val result: String = "teste"

      result must_==("teste")
    }
  }

  "Uma super classe " should {
    "alterar atributos da sublclasse SubClass com _set " in {
      val expected = 1
      val subClass = new SubClass()
      subClass.__set("attribute", expected)
      val result = subClass.getAttribute

      result must_==(expected)
    }
    "Criar uma instancia de sua subclasse com __empty " in {
      val expected = 0
      val subClass : SubClass = SubClass.__empty()
      val result = subClass.getAttribute
      result must_==(expected)
    }
  }
}