Mockk: Verify + argument captor

[VictorAlbertos]

Is there a way to verify that some method has been called with specific arguments?

Given this class:

class Log {
    fun event(name: String): Boolean = true
}

With Mockito (using the wrapper mockito-kotlin) I can verify that the method was called with some specific argument:

@Test
fun verifyMockito() {
    val log = mock<Log>()
    whenever(log.event(logName)).thenReturn(false)

    log.event(logName)

    verify(log, times(1)).event(com.nhaarman.mockito_kotlin.check {
        assert(logName == it)
    })
}

But using mockk I don't know how to do it without mocking at the same time. Actually, it's not verifying that that method has been called:

@Test
fun verifyMockk() {
    val log = mockk<Log>()

    //even if I remove this line the test passes, because it is not verifying.
    log.event(logName)

    //mocking
    every { log.event(logName) } returns false

    val slot = slot<String>()
    //verification but also forcing me to mock again
    every {  log.event(name = capture(slot))
    } answers {
        assert(slot.captured == logName)
        //have to return the type (again?)
        true
    }
}

Maybe I'm missing something. But I was not able to find a way of doing this on the docs. How should I address this use case as client of this library?

[oleksiyp]

It should be very easy:

verify {
  log.event(logName)
}

[VictorAlbertos]

My example was not good 😅. Imagine you don't have access to logName. How would you do it then? That's the real problem that I'm able to tackle with mockito, but using your library I'm a bit confused. This is how I ended up doing it. Not sure if it is the proper way although.

@Test
fun verifyMockk() {
    val log = mockk<Log>()

    //logName instance is not accesible from this scope (indirection layers hide this as an internal detail)
    log.event(logName)

    val slot = slot<String>()
    every { log.event(name = capture(slot)) } answers { true }

    io.mockk.verify(exactly = 1) { log.event(any()) }
    assert(slot.captured == "logName")
}

[oleksiyp]

You can capture in verify, or use assert matcher. Dont remeber right what exact name it has

[VictorAlbertos]

I see. Much better 👍 Thanks!

@Test
fun verifyMockk() {
    val log = mockk<Log>()
    log.event(logName)

    val slot = slot<String>()
    verify(exactly = 1) { log.event(name = capture(slot)) }
    assert(slot.captured == logName)
}

[alex-arana]

Since v1.9.+ you can also do something like this:

@Test
fun verifyMockk() {
    val log = mockk<Log> {
        every { event(any()) } just Runs
    }
    log.event(logName)

    verify(exactly = 1) { log.event(
        withArg {
            assertThat(it).isEqualTo(logName)
        })
    }
}