Unable to mock wrapped function with value class param

[Rattenkrieg]

Consider following code

@JvmInline
value class DummyValue(val value: Int)

class DummyService {

    fun processValue(value: DummyValue): DummyValue {
        return value
    }

    fun callWrapped(value: DummyValue) = processValue(value)
}

fun main() {

    val mock = mockk<DummyService>()

    every { mock.processValue(DummyValue(1)) } returns DummyValue(42)

    println(mock.callWrapped(DummyValue(1)))

    verify { mock.processValue(DummyValue(1)) }
}

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

Expected Behavior

DummyValue(42) printed

Current Behavior

Exception in thread "main" io.mockk.MockKException: no answer found for: DummyService(#1).callWrapped--ycYzh0(1)

• MockK version: 1.12.0
• OS: macOS BigSur 11.4
• Kotlin version: 1.5.20
• JDK version: Adopt OpenJDK 16.0.1
• JUnit version: I'm running simple main method
• Type of test: I'm running simple main method

[d35h]

I don't think that the mocking is the problem here, since you're using mockk, it tries to mock all the methods of DummyService, for the purpose of mocking only certain methods (in your case processValue only), you should be using spyk, i.e.:

    fun main() {
        val mock = spyk<DummyService>()
        every { mock.processValue(DummyValue(1)) } returns DummyValue(42)
        println(mock.callWrapped(DummyValue(1)))
        verify { mock.processValue(DummyValue(1)) }
    }

However, it won't work because of this https://youtrack.jetbrains.com/issue/KT-46477#focus=Comments-27-4952485.0-0

As a temporary workaround until Kotlin 1.5.30-M1 is released, you could make your return type nullable:

 fun processValue(value: DummyValue): DummyValue? = value

Or in case you really want to use mockk, you can make it call the original implementation by doing this:

    fun main() {
        val mock = mockk<DummyService>()
        every { mock.processValue(DummyValue(1)) } returns DummyValue(42)
        every { mock.callWrapped(DummyValue(1)) } answers { callOriginal() }
        println(mock.callWrapped(DummyValue(1)))
        verify { mock.processValue(DummyValue(1)) }
    }

[Rattenkrieg]

Thanks @d35h actually my issue is more complicated one and I tried to come up with a simple demo that has an issue on it's own as you demonstrated. For now I've changed the test setup to avoid mocking problematic dependencies and I'll try the spyk approach as soon as 1.5.30 is shipped.

[stale]

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