Hello! <https://stackoverflow.com/questions/74400503/how-do-i-mock-a-kotlin-function-type-with-mockk...

# mockk

[dmcg]

Hello!
https://stackoverflow.com/questions/74400503/how-do-i-mock-a-kotlin-function-type-with-mockk

[Emil Kantis]

Why mock the function type instead of just sending the function which returns your mocked result?

[dmcg]

What do you mean by sending the function? Something like ``PricedStockListLoader(stock, { _ -> Price(666) })` ?

[Emil Kantis]

yes

[dmcg]

I was trying to be consistent between the collaborators, and to show that you could mockk functions, only to find that I can’t!

[Emil Kantis]

Gotcha.. this works for me:

test("mock function type") {
   val mockedFunction = mockk<(Int) -> String>()
   every { mockedFunction.invoke(5) } returns "hello"
   mockedFunction(5) shouldBe "hello"
}

(Using Kotest, not sure if JUnit is messing with anything)

[Emil Kantis]

Using MockK 1.13.2

[dmcg]

Hmm, then I wonder if JUnit is messing with something.

[dmcg]

Or rather, kotest is compensating for something

[dmcg]

My gut says coroutines are marching in the direction of this problem

[Emil Kantis]

Not sure where coroutines might mess with things. No suspending functions in sight afaik?

[dmcg]

I was thinking that kotest is coroutine aware and JUnit isn’t…

[Emil Kantis]

It is 🙂

[dmcg]

but this is fine:

class Delme {
    @Test
    fun test() {
        val mockedFunction = mockk<(Int) -> String>()
        every { mockedFunction.invoke(5) } returns "hello"
        assertEquals("hello", mockedFunction(5))
    }
}

[Emil Kantis]

what is anItem in your case?

[dmcg]

its a plain old data class

[dmcg]

I really appreciate the help, but have to do an urgent thing. Will report back on investigations.

[Emil Kantis]

No worries, and appreciate if you get back with the results 🙂

[Emil Kantis]

If you push PricedStockListLoaderTest to Github I can take another look at it 🙂

[dmcg]

Some awesome detective work on SO by someone (@irus?) https://stackoverflow.com/a/74414374/97777

[dmcg]

I’ve filed https://github.com/mockk/mockk/issues/977