How to stub methods sooner than @Before block?

Question

I initialize my ViewModel at top level, and as it initializes, it calls its init {} block, which then calls methods that I stub in @Before block.

Although all the tests are passed, NullPointerExceptions is thrown in methods that I call in init {}. I tried to lateinit my ViewModel in @Before block. It didn't work.

// AViewModelTest.kt
private val repoMock: ARepository = mock()
private val viewModel: AViewModel = AViewModel(repoMock)

@Before
fun setup() {
    // method stubbing
    `when`(repoMock.getSmth()).thenReturn(response)
}


// AViewModel.kt
constructor(repo: ARepository) {}

init {
    onStartLoading(repo)
}

fun onStartLoading(repo: ARepository) {
    val response = repo.getSmth()
    handleResponse(response) // response is null here -> NullPointerException
}

You could try the @BeforeClass annotation: https://stackoverflow.com/questions/20295578/difference-between-before-beforeclass-beforeeach-and-beforeall — MasterQueue, Nov 23 '18 at 12:13
Please read "How to create a [mcve]". Then use the [edit] link to improve your question (do not add more information via comments). Otherwise we are not able to answer your question and help you. — GhostCat, Nov 23 '18 at 13:27
`init` blocks are equivalent to constructor bodies, and so they will always be called before any methods. This is expected behavior. `repo` is `null` when `onStartLoading(repo)` is called from `init`. — RussHWolf, Nov 26 '18 at 03:37
@Brucelet I tried to `lateinit viewModel` in `@Before` block, but it didn't work for some reason. — madim, Nov 26 '18 at 03:40
The `@Before` block is called after `init`, so initializing in `@Before` doesn't help you here. Probably a better solution is to move the code from the `init` block into the `setup()` function instead. — RussHWolf, Nov 26 '18 at 03:46

madim · Accepted Answer · 2018-11-28T03:42:57.127

0

In the end, lateinit in @Before did the thing. The problem occurred because I had an implicit reference to Android Context in my ViewModel.

edited Nov 28 '18 at 03:42

answered Nov 26 '18 at 09:38

madim

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How to stub methods sooner than @Before block?

1 Answers1