Mock private property with mockk throws an excpetion

Question

I'm using mockk for my testing in kotlin. But I can't seem to override a private property in a spy object.

I have this object

private val driverMapSnapshotMap: MutableMap<Int, SnapshotImage> = mutableMapOf()

in a class that I spy on using

viewModel = spyk(DriverListViewModel(), recordPrivateCalls = true)

But when I try to make it fill up with mock values I get an error

every {
    viewModel getProperty "driverMapSnapshotMap"
} returns(mapOf(1 to mockkClass(SnapshotImage::class)))

The error I get

io.mockk.MockKException: Missing calls inside every { ... } block.

Any thoughts?

score 3 · Answer 1 · answered Jan 19 '21 at 07:16

Here is a solution to access private fields in Mockk for classes( for objects it is even simpler )

 class SaySomething {
    private val prefix by lazy { "Here is what I have to say: "}

    fun say( phrase : String ) : String {
        return prefix+phrase;
    }
}

  @Before
fun setUp() = MockKAnnotations.init(this, relaxUnitFun = true)

 @Test
fun SaySomething_test() {

    mockkConstructor(SaySomething::class)
    every { anyConstructed<SaySomething>() getProperty "prefix" } propertyType String::class returns "I don't want to say anything, but still: "

    val ss = SaySomething()
    assertThat( ss.say("Life is short, make most of it"), containsString( "I don't want to say anything"))
}

score 2 · Accepted Answer · answered Nov 25 '19 at 10:53

2

It is nearly impossible to mock private properties as they don't have getter methods attached. This is kind of Kotlin optimization and solution is major change.

Here is issue opened for that with the same problem:

https://github.com/mockk/mockk/issues/263

answered Nov 25 '19 at 10:53

Misha Akopov

12,241
27
68
82

2

Yes, sorry for not updating but I ended up accessing the private properties myself through reflection – orelzion Nov 25 '19 at 14:02
Ohhh, I see. It is sad to use reflection for such cases. But if you have no straightforward way of doing it, what can we do. I am happy you found "solution" – Misha Akopov Nov 25 '19 at 14:27

score 0 · Answer 3 · answered Nov 19 '19 at 12:45

0

It should be

every {
viewModel getProperty "driverMapSnapshotMap"
} returns mock(DriverRemoteModel::class)

answered Nov 19 '19 at 12:45

sasikumar

12,540
3
28
48

"driverMapSnapshotMap" is a mutableMap, so I am returning a map object – orelzion Nov 19 '19 at 12:56
Oh but now I see, I mock the wrong object here, it should be `SnapshotImage` – orelzion Nov 19 '19 at 13:28
OK, changed it to the right object, but still no success – orelzion Nov 19 '19 at 18:56

Mock private property with mockk throws an excpetion

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