Mock (lazy) vals

[rkaercher]

I want to mock classes having vals and lazy vals. When I try this:

import org.scalamock.scalatest.MockFactory
import org.scalatest.FunSpec

class LazyValTest extends FunSpec with MockFactory {

  describe("A mocked instance should have its lazy vals mockable.") {

    class ClassToMock {
      lazy val mockMe = 5 * 3
      val mockMeToo = 5

      def getLazyVal = mockMe
      def getNormalVal = mockMeToo
    }

    val mockedInstance = stub[ClassToMock]

    (mockedInstance.getNormalVal _) expects () returning 3

    (mockedInstance.getLazyVal _) expects () returning 5

    (mockedInstance._mockMe _) expects () returning 5

    (mockedInstance.mockMeToo _) expects () returning 3
  }

}

I get the following compile error:
_ must follow method; cannot follow mockedInstance.mockMe.type

Am I doing this wrong or is this an error?

Thanks in advance for your help.

[paulbutcher]

This is expected behaviour because Scala doesn't allow a lazy val to be overridden with a def. It's possible that I might be able to make it work in ScalaMock4, however, which I've just started working on.

[barkhorn]

This is now mentioned as a known limitation in the FAQ: http://scalamock.org/user-guide/faq/

[steinybot]

There is a comment from @paulbutcher on StackOverflow about scalameta making this possible. Is this now something that could be implemented?

[barkhorn]

ScalaMeta is an interesting library but it will require significant rewrites to make use of it. ScalaMock relies on whitebox macros internally, which aren't exactly compatible and we'd need to transition away from that. Still worth looking at.

[barkhorn]

a Scala val cannot be overridden by a def, so this feature doesn't fit into ScalaMock really, even with the potential use of ScalaMeta. Assuming the val is not final, you can just subclass it yourself so i don't really see a strong argument for ScalaMock to provide special handling. Example:

class ClazzIWantToMock {
  val thingIdlikeToOverride: Int = 5
}

class MockedClazz extends ClazzIWantToMock {
  override val thingIdlikeToOverride= 99
}