lateinit property has not been initialized

Hello,

I have the following class

@Path("/canceling")
class CancelResource {

  @Inject
  lateinit var cancelManager: CancelManager

  @POST
  @Path("{id}")
  fun cancelItem(@PathParam("id") id: String){
    cancelManager.addItem(id)
  }
}

A CancelManager which is an @ApplicationScoped class

@ApplicationScoped
class CancelManager {
  var ids = setOf<String>()

  fun addItem(id: String) {
    ids = ids.plus(id)
  }
}

To test the CancelResource I need to mock the CancelManager. I did the following:

Test :

internal class CancelResourceTest {
  @MockK
  lateinit var cancelManager: CancelManager

  @InjectMockKs
  lateinit var service: CancelResource

  @BeforeEach
  fun init() {
    MockKAnnotations.init(this)
    service = CancelResource()
  }

  @Test
  fun runTest() {
    val id = "dummy item"
    justRun { cancelManager.addItem(id) }

    service.cancelItem(id)

    verify { cancelManager.addItem(id) }
  }
}

Expected behavior: Correcly mocking the injection

Current behavior It gives the following error kotlin.UninitializedPropertyAccessException: lateinit property cancelManager has not been initialized

What’s wrong?

---

MockK version: 1.10.0 Kotlin version: 1.3.72 JUnit5: junit-jupiter: 5.7.0 and junit-platform: 1.7.0

[d35h]

I think that your problem is due to the fact that you’re trying to initialize CancelResource yourself, which should be the responsibility of the code you call in @BeforeEach block that is MockKAnnotations.init(this)

Delegate the initiation of mocks to the MockK framework, this code should work:

  @MockK
  lateinit var cancelManager: CancelManager

  @InjectMockKs
  lateinit var service: CancelResource

 @BeforeEach
  fun init() {
    MockKAnnotations.init(this)
  }

  @Test
  fun runTest() {
    val id = "dummy item"
    justRun { cancelManager.addItem(id) }

    service.cancelItem(id)

    verify { cancelManager.addItem(id) }
  }

Also, I would highly recommend you to go over the best practices for unit testing in Kotlin, in your case specifically the Create Mocks Once chapter, which suggests to get rid of vars and recreation of mocks for each tests and clear all mocks before a test instead: https://phauer.com/2018/best-practices-unit-testing-kotlin/#create-mocks-once

This being said, I would suggest to make a refactoring of your code (I hope you don’t mind) the following way, so that the ideas in the guide above can be applied:

open class CancelResourceTest {

    private val cancelManager: CancelManager = mockk(relaxed = true)

    private val service: CancelResource = CancelResource(cancelManager)

    @BeforeEach
    fun setUp() {
        clearAllMocks()
    }

    @Test
    fun runTest() {
        val id = "dummy item"
        cancelManager.addItem(id)

        service.cancelItem(id)

        verify { cancelManager.addItem(id) }
    }
}

@Path("/canceling")
class CancelResource(@Inject val cancelManager: CancelManager) {

    @POST
    @Path("{id}")
    fun cancelItem(@PathParam("id") id: String){
        cancelManager.addItem(id)
    }
}

@ApplicationScoped
class CancelManager {
    var ids = setOf<String>()

    fun addItem(id: String) {
        ids = ids.plus(id)
    }
}

I hope it helps

[Raibaz]

I think your CancelManager should be annotated with @MockK, as it’s the class you’re mocking, and service should be annotated with @InjectMocks, as it’s the class you’re injecting mocks into.

And yes, you need to call MockKAnnotations.init(this) in your init function for the annotations to be initialized.

Hope this helps