Wrong value when mocking kotlin.Result

[steven-carrell]

Prerequisites

Please answer the following questions for yourself before submitting an issue.

• I am running the latest version
• I checked the documentation and found no answer
• I checked to make sure that this issue has not already been filed

Failure Information (for bugs)

In mockk 1.12.4 I was able to mock a kotlin.Response return value on a function and get the generic value from it.

1.12.5 seems to have broken this and regardless of the Response.success(x) value, success always folds to a boolean false.

Code below.

Context

• MockK version: 1.12.5
• OS: macOS 11.5.2
• Kotlin version: 1.7.10
• JDK version: 11
• JUnit version: 4.13.2
• Type of test: unit test

Minimal reproducible code (the gist of this issue)

// -----------------------[ GRADLE DEFINITIONS ] -----------------------
dependencies {
    testImplementation("org.hamcrest:hamcrest-library:2.2")
    testImplementation("junit:junit:4.13.2")
    testImplementation("io.mockk:mockk:1.12.5")
}
// -----------------------[ YOUR CODE STARTS HERE ] -----------------------
import io.mockk.every
import io.mockk.mockk
import org.hamcrest.CoreMatchers.equalTo
import org.hamcrest.MatcherAssert.assertThat
import org.junit.Test

class ResultTest {
    interface ToMock {
        fun returnsResult(): kotlin.Result<String>
    }

    @Test
    fun `result value`() {
        val value = Result.success("something")
        val toMock = mockk<ToMock> {
            every { returnsResult() } returns value
        }
        // Expected: <Success(something)>
        //      but: was <Success(false)>
        assertThat(toMock.returnsResult(), equalTo(value))
    }
}
// -----------------------[ YOUR CODE ENDS HERE ] -----------------------

[svenjacobs]

I'm facing the same issue. The following test works with 1.12.4 but not with 1.12.5:

interface Source {
    fun getData(): Result<Boolean>
}

interface View {
    fun showError()
    fun showData()
}

class TestSubject(
    private val source: Source,
    private val view: View,
) {

    fun execute() {
        val result = source.getData()

        when {
            result.isFailure -> view.showError()
            result.getOrThrow() -> view.showData()
        }
    }
}

class ValueClassTest : WordSpec({

    val source = mockk<Source>()
    val view = mockk<View>()
    val subject = TestSubject(source, view)

    beforeEach {
        clearMocks(
            source,
            view,
        )
    }

    "execute" should {

        "show data" {
            every { source.getData() } returns Result.success(true)

            subject.execute()

            verify {
                view.showData()
            }
        }

        "show error" {
            every { source.getData() } returns Result.failure(NullPointerException())

            subject.execute()

            verify {
                view.showError()
            }
        }
    }
})

[ikurek]

I'm facing the same issue with 1.12.5. Everything works fine in 1.12.4

[qoomon]

Should be fixed by #872

[qoomon]

It was fixed with recent version 1.12.6

[sschuberth]

It was fixed with recent version 1.12.6

Unfortunately, something apparently went wrong with publishing that release.

[steven-carrell]

Looks good on 1.12.7

[pphilipp]

Seems like the issue comes back. I have the Result.failure(Exception()) which wrapped with Result.success(Result.failure(Exception())).

version io.mockk:mockk:1.13.2

[caeus]

Why was this closed, if not fixed?

[sschuberth]

Why was this closed, if not fixed?

Read above, there seems to be a regression.

[JWvanV]

I also encountered this issue recently in io.mockk:mockk:1.13.5:

abstract class StateHolder<S>(defaultState: S) {

    private val mutableState = MutableStateFlow(defaultState)
    val stateFlow = mutableState.asStateFlow()

    val currentState: S
        get() = mutableState.value
}

class LoadingStateHolder() : StateHolder<Result<LoadingState>>(Result.failure(Exception())) {}

@RelaxedMockK
private lateinit var stateHolder: LoadingStateHolder

every { stateHolder.currentState } returns Result.failure(Exception("No state"))

Error: Cannot invoke "kotlin.Result.unbox-impl()" because the return value of "LoadingStateHolder.getCurrentState()" is null