Mocking final field with Kotlin

Question

I'm newbie on Kotlin, Mockito. Below code has an error which is caused by engine, an immutable field that is not mocked.

I spent a lot of time trying to solve this problem. I found that a way of mocking works, until I don't understand and don't satisfy that.

move a field to constructor. class Car(val engine: Engine) { ... }
change to mutable field. private var engine = Engine()

Is there any other way?

class Car {

  private val engine = Engine() // here
  var state: String? = null

  fun move() {
    state = engine.state
  }
}

@RunWith(MockitoJUnitRunner::class)
class CarTest {

  @Mock private lateinit var mockedEngine: Engine

  @InjectMocks private val car = Car()

  @Test
  fun test() {
    `when`.(mockedEngine.state).thenReturn("run")
    car.move()
    assertEquals("run", car.state)
  }
}

Possible duplicate of [How to mock final field? mockito/powermock](https://stackoverflow.com/questions/23629766/how-to-mock-final-field-mockito-powermock) — crgarridos, Oct 11 '17 at 12:33
Possible duplicate of [How to mock final class with Mockito 2 on Java Module in Android project?](https://stackoverflow.com/questions/43306269/how-to-mock-final-class-with-mockito-2-on-java-module-in-android-project) — zsmb13, Oct 11 '17 at 16:05
Is final field equally treated final class or final static? I suspect constructor issue for a `car` with injectMocks. — illusionJJ, Oct 12 '17 at 12:47

score 1 · Accepted Answer · answered Oct 11 '17 at 16:05

1

I think you've already answered your question. There is no other good solution. What you suggest as the options (preferably first one) is properly designed class to be testable.

answered Oct 11 '17 at 16:05

palasjir

208
1
8

Mocking final field with Kotlin

1 Answers1