Tagged: mockito

Mocking nested objects with mockito

Yes, I know its a code smell. But I live in the real world, and sometimes you need to mock nested objects. This is a scenario like:

when(a.b.c.d).thenReturn(e)

The usual pattern here is to create a mock for each object and return the previous mock:

val a = mock[A]
val b = mock[B]
val c = mock[C]
val d = mock[D]

when(a.b).thenReturn(b)
when(b.c).thenReturn(c)
when(c.d).thenReturn(d)

But again, in the real world the signatures are longer, the types are nastier, and its never quite so clean. I figured I’d sit down and solve this for myself once and for all and came up with:

import org.junit.runner.RunWith
import org.mockito.Mockito
import org.scalatest.junit.JUnitRunner
import org.scalatest.{FlatSpec, Matchers}

@RunWith(classOf[JUnitRunner])
class Tests extends FlatSpec with Matchers {
  "Mockito" should "proxy nested objects" in {
    val parent = Mocks.mock[Parent]

    Mockito.when(
      parent.
        mock(_.getChild1).
        mock(_.getChild2).
        mock(_.getChild3).
        value.doWork()
    ).thenReturn(3)

    parent.value.getChild1.getChild2.getChild3.doWork() shouldEqual 3
  }
}

class Child3 {
  def doWork(): Int = 0
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