Hi guys, new Kotlin developer here. I have the fol...

# getting-started

[ptheocharis]

Hi guys, new Kotlin developer here. I have the following issue: I have simple Greeting object, allong with a GreetingController like the below:

data class GreetingDto(
  val greeting: String? = null,
  val name: String? = null
)

class GreetingController {

  @GetMapping("/greeting")
  fun greeting(): GreetingDto {
    return GreetingDto("Hello", "World")
  }
}

And I have unit test in Groovy, running with spock:

class GreetingControllerSpec extends Specification {
  GreetingController greetingController

  def setup() {
    greetingController = new GreetingController()
  }

  def "test greeting"() {
    given:
      GreetingDto result
      GreetingDto expected = expected()
    when:
      result = greetingController.greeting()
    then:
      result == expected
  }

  GreetingDto expected() {
    new GreetingDto(
      greeting: "Hello",
      name: "World"
    )
  }
}

My problem is that the fields in the constructor which are defined with val, cannot be accessed by the Groovy constructor and I get this exception:

groovy.lang.ReadOnlyPropertyException: Cannot set readonly property: greeting for class: app.greeting.GreetingDto