How to call real method on a stub

Question

Is there a way to call a real method on a stubbed object with scalamock?

I would like to be able to do something like this:

class MySpec extends FunSpec with Matchers with MockFactory {
  trait MyTrait {
    def f1: Int
    def f2: Int = f1
  }

  describe("my feature") {
    it("should work") {
      val t = stub[MyTrait]
      (t.f1 _).when().returns(15)
      // I would like to do the following:
      // (t.f2 _).when().callRealMethod()
      t.f2 should be (15)
    }
  }
}

Note: I was able to work around the issue by making f2 final but I would like to know if there is a way to do it without changing the code under test.

Answer 1

The pattern that I could recommend is to make the function you don't want to mock final, as you suggested. But rather than doing this in the real code, you use a subclass that's only used for test purposes, e.g. like this:

import org.scalamock.scalatest.MockFactory
import org.scalatest.FunSuite
import PartialMockingTest._

class PartialMockingTest extends FunSuite with MockFactory {

  test("test case") {

    class PartFinalCls extends Cls {
      override final def B(): Int = super.B()
    }

    val f = stub[PartFinalCls]
    f.A _ when 7 returns 5
    assert(f.B() == 6)
  }

}

object PartialMockingTest {
  class Cls {
    def A(dummy: Int): Int = 5

    def B(): Int = A(7) + 1
  }
}

Answer 2

Unfortunately, spying is not available: https://github.com/paulbutcher/ScalaMock/issues/249

Answer 3

Unfortunately ScalaMock does not provide the «callRealMethod» feature.

If ever a change of testing framework is possible you have an alternative way with mockito-scala and the MockitoSugar trait that can provide you with what you want.

Your code would look like to :

class MySpec extends FunSpec with MockitoSugar with Matchers {

  trait MyTrait {
    def f1: String = "mock"

    def f2: String = "not a mock"
  }


  describe("my feature") {
    it("should work") {
      val t = mock[MyTrait]
      when(t.f1).thenReturn("mocked")
      t.f1 shouldBe "mocked"
      when(t.f2) thenCallRealMethod()
      t.f2 shouldBe "not a mock"
    }
  }

You need to add mockito scala as a dependency tho. (sbt way)

 "org.mockito" %% "mockito-scala" % "${version}",
 "org.mockito" %% "mockito-scala-scalatest" % "${version}"