Hey! I’m struggling a bit making Kotest, Koin and ...

# koin

[Dmytro Koval]

Hey!
I’m struggling a bit making Kotest, Koin and Ktor work together. Specifically overriding a single defined in the main application with a Mockk in tests. I was expecting Koin to pickup the customerServiceMock instead of the production CustomerService , but it doesn’t.

Here’s a sample of the test:

class APITest :
    FunSpec(),
    KoinTest {

    override fun extensions(): List<Extension> = listOf(
        WireMockListener(jwksWireMockServer, ListenerMode.PER_SPEC),
        KoinExtension(
            module = module {},
            mockProvider = { mockkClass(it, relaxed = true) },
            mode = KoinLifecycleMode.Root,
        ),
    )

    init {
        val testDb = install(DatabaseTestConfig.jdbcTestExtension).createTestDatabase()

        val appConfig =
            listOf(
                ApplicationConfig("application.test.conf"),
                testDb.applicationConfig,
                JwksWireMockSetup.appConfig,
            ).reduce(ApplicationConfig::mergeWith)

        test("Empty tables and no defaults should return empty results") {
            testApplication {
                environment {
                    config = appConfig
                }

                val customerServiceMock = declareMock<CustomerService>()

                coEvery { customerServiceMock.getCustomer(any()) }.returns(Customer(CustomerId("1"), 30))

                val cli = createTestClient()

                cli.get("/api/v1/recommendations?customerId=1").apply {
                    status shouldBe HttpStatusCode.OK
                    body<Recommendations>() shouldBe Recommendations.empty()
                }
            }
        }
    }
}

[Dmytro Koval]

@arnaud.giuliani
I have a reproduction sample here: https://github.com/mityakoval/KoinKotestSample

[Dmytro Koval]

Not sure if it’s a bug or a feature, but I noticed that the issue arises if routing is configured in complicated-ish way.

import com.example.routing.testRouting
import io.ktor.server.application.Application

fun Application.configureRouting() {
    testRouting()
}

...

import com.example.services.ServiceA
import com.example.services.ServiceB
import io.ktor.http.HttpStatusCode
import io.ktor.server.application.Application
import io.ktor.server.application.call
import io.ktor.server.response.respond
import io.ktor.server.routing.Route
import io.ktor.server.routing.get
import io.ktor.server.routing.routing
import kotlinx.serialization.Serializable
import org.koin.ktor.ext.inject

fun Application.testRouting() {
    routing {
        val serviceA by inject<ServiceA>()
        val serviceB by inject<ServiceB>()
        test(serviceA, serviceB)
    }
}

@Serializable
data class Response(val a: String, val b: String)


fun Route.test(serviceA: ServiceA, serviceB: ServiceB) {
    get("/test") {
        call.respond(status = HttpStatusCode.OK, Response(serviceA.identify(), serviceB.identify()))
    }
}

[Dmytro Koval]

If I just stuff all routes in routing {} in configureRouting() the mocks are injected correctly.

[arnaud.giuliani]

yeah, I'vn't tried this kind of test with kotest. Perhaps @LeoColman?

[LeoColman]

I believe the problem lies in Ktor's `testApplication`:

Note: If you have the application. conf file in the resources folder, testApplication loads all modules and properties specified in the configuration file automatically.

Your application.conf is defined as

ktor {
  deployment {
    port = 8080
  }
  application {
    modules = [com.example.ApplicationKt.module]
  }
}

and com.example.ApplicationKt.module ends up calling

fun Application.configureKoin() = install(Koin) {
    slf4jLogger()

    val config = module {
        single<ServiceA> { ServiceA() }
        single<ServiceB> { ServiceB() }
    }

    modules(config)
}

So by the time your test starts, Koin is already ready to go with an actual instance of ServiceB and it's no longer possible to replace it with another implementation by using the regular declareMock.

My guess for your work around is that you skipped the testApplication bit that sets Koin up.

I'm not an ace in Ktor, so I might have missed a point