Coroutine/suspend function mocking support

[dave08]

If you use non-inline lambdas that are not declared as suspend, the runBlocking { } around the test function doesn't help, rather we need to mock { on { runBlocking { suspendFun() } } } for each mock...

[nhaarman]

Could you post a more elaborate example?

[dave08]

interface AccountRepository {
    suspend fun getAccountId(deviceNo: String): Int
}

class SUT(val repo: AccountRepository) {
   fun something() {
        launch(CommonPool) { println(repo.getAccountId("0000")) }
  }
}

// Test function
val repoMock:AccountRepo = mock { onGeneric { runBlocking { getAccountId(any()) } } doReturn 3300 }

val sut = SUT(repoMock)
sut.something()

// Do some assertions on mock

[dave08]

If the mock and onGeneric lambdas were either suspend functions or inline, then I wouldn't need to put runBlocking inside the onGeneric for every function, I could just surround the whole mock {} with runBlocking, it would be much cleaner.

[ghost]

Isn't this gonna be sort of hard to implement if you want to have the library compatible with pre 1.1 kotlin? Maybe soon Gradle magic?

[ghost]

Or maybe it's enough to just make them inline.

[dave08]

It might be enough to make them into extension functions that are inline, I'm just not sure about nested dsl working that way... בתאריך 2 באוק׳ 2017 7:55 PM,‏ "540Grunkspin" <notifications@github.com> כתב:

…

Or maybe it's enough to just make them inline. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#205 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAxq9K9dyJM2_m5AXsAegppoxTWSGM6gks5soRWZgaJpZM4PnKkt> .

[ghost]

I created a pull request for a suggested fix. Seems like all the previous tests are passing but still waiting for the CI to run.

Not sure if this is exactly what you wanted. There is an example test in there as well.

[dave08]

Thanks, I'm on vacation for a week, but when I get back I'll try it out! I'm sure it'll help lots of people, if coroutines pick up as much as Kotlin did... בתאריך 3 באוק׳ 2017 6:46 PM,‏ "540Grunkspin" <notifications@github.com> כתב:

…

I created a pull request for a suggested fix. Seems like all the previous tests are passing but still waiting for the CI to run. Not sure if this is exactly what you wanted. There is an example test in there as well. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#205 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAxq9DnzOWdWO4WH9KuZBtIdAVPun-_vks5solbQgaJpZM4PnKkt> .

[PaulWoitaschek]

Any news on this? It's the same with given

    given { runBlocking { mockLoginManager.refreshToken() } }
        .willReturn {
          TokenFactory.create(expired = false)
        }

Creates quite some noise whenever there is a suspending function.

[ghost]

I tried to switch to inline but that didn't really fix the problem, not sure if I'm smart or knowledgeable enough to fix it. Feel free to pick up where I left off. See my linked pull request.

[nhaarman]

I don't really use coroutines much myself. I can suggest this solution:

fun <T : Any, R> KStubbing<T>.onBlocking(
      m: suspend T.() -> R
): OngoingStubbing<R> {
    return runBlocking { Mockito.`when`(mock.m()) }
}

.. but I don't know if it covers all scenarios. The following test passes:

interface SomeInterface {

    suspend fun foo(): Int
}

@Test
fun test() = runBlocking {
    val m = mock<SomeInterface> {
        onBlocking { foo() } doReturn 42
    }

    val result = m.foo()

    expect(result).toBe(42)
}

[bohsen]

The above solution works.

[ZakTaccardi]

what if I want to control when the suspending function returns? is this possible?

[carterhudson]

@nhaarman
So, "mock" is private in KStubbing, thus that extension function doesn't seem to be an option. Would I need to clone the project locally to implement this, or is it going to be in a future release? In my case, it helped expose that my domain and data layers should probably return Deferred instances instead of making suspend functions part of their API, but I can imagine this is still a pain point for someone else somewhere else.

[juanchosaravia]

Pointing to this version I was able to use directly the onBlocking function:
"com.nhaarman.mockitokotlin2:mockito-kotlin:2.0.0-alpha04"

I tried using latest version:
"com.nhaarman.mockitokotlin2:mockito-kotlin:2.0.0-RC1"
but onBlocking is not available anymore and I don't know if there is another function that is replacing this.

[mochadwi]

.. but I don't know if it covers all scenarios. The following test passes:

interface SomeInterface {

    suspend fun foo(): Int
}

@Test
fun test() = runBlocking {
    val m = mock<SomeInterface> {
        onBlocking { foo() } doReturn 42
    }

    val result = m.foo()

    expect(result).toBe(42)
}

I cannot find this method signature in your library @nhaarman , is this an assertion/verify mocking?

EDITED:
I cannot find expect(result).toBe(42) method ..

[nhaarman]

.. but I don't know if it covers all scenarios. The following test passes:

interface SomeInterface {

    suspend fun foo(): Int
}

@Test
fun test() = runBlocking {
    val m = mock<SomeInterface> {
        onBlocking { foo() } doReturn 42
    }

    val result = m.foo()

    expect(result).toBe(42)
}

I cannot find this method signature in your library @nhaarman , is this an assertion/verify mocking?

See https://github.com/nhaarman/expect.kt

[mochadwi]

Nice thanks a lot @nhaarman

[MedetZhakupov]

I don't really use coroutines much myself. I can suggest this solution:

fun <T : Any, R> KStubbing<T>.onBlocking(
      m: suspend T.() -> R
): OngoingStubbing<R> {
    return runBlocking { Mockito.`when`(mock.m()) }
}

.. but I don't know if it covers all scenarios. The following test passes:

interface SomeInterface {

    suspend fun foo(): Int
}

@Test
fun test() = runBlocking {
    val m = mock<SomeInterface> {
        onBlocking { foo() } doReturn 42
    }

    val result = m.foo()

    expect(result).toBe(42)
}

While this might work fine for interface's suspend function it's not working for me in mocking below suspend function type

someFunction: suspend () -> Boolean

It throws NullPointerException. If I remove suspend keyword and use simple mocking like

on { invoke() }.doReturn { true }

it also throws NullPointerException but when I change it to

onGeneric { invoke() }.doReturn { true }

then it works fine. In suspend case I am not sure what might be the alternative for that. Anyone has any clue how I can approach this?