Using Koin for Ktor-Client in Android: Missing type 'io.ktor.client.engine.HttpClientEngine'

Question

I could use some help understanding why this module for a ktor client fails -

fun provideKtorClient() = HttpClient(OkHttp) {
    install(ContentNegotiation) {
        json()
    }
}

val ktorModule = module {
    single { provideKtorClient() }
}

@Test
    fun checkKtorModule() {
        ktorModule.verify()
    }

A simple test fails with the error -

org.koin.test.verify.MissingKoinDefinitionException: Missing type 'io.ktor.client.engine.HttpClientEngine' for class 'io.ktor.client.HttpClient' in definition '\[Singleton:'io.ktor.client.HttpClient'\]'

I tried creating an HttpClientEngine provider following the error message. However, this led to chasing even more objects and providers down the rabbit hole. My impression was that objects like ktor's OkHttp shouldn't need any further initialization. This makes me think I'm missing something larger here? Thanks!

EDIT / Answer

When writing a simple unit test, the extra types need to be provided for initialisation like so -

@Test
fun checkKtorModule() {
    ktorModule.verify(
        extraTypes = listOf(
            io.ktor.client.engine.HttpClientEngine::class,
            io.ktor.client.HttpClientConfig::class
        )
    )
}

If running an Android instrumentation test, these classes load fine with no other specification needed -

@Test
fun checkAllModules() {
    koinApplication{
        modules(appModule, ktorModule)
        checkModules(){
            withInstance<Ordering.Context>()
            withInstance<Application>()
            withInstance<SavedStateHandle>()
        }
    }
}

Thanks for all the help!

Answer 1

I've made it work by providing the dependencies for the HttpClient's constructor but I'm not sure if this is a right way to do it.

fun provideKtorClient() = HttpClient {
    install(ContentNegotiation) {
        json()
    }
}

val ktorModule = module {
    single { provideKtorClient() }
    single<HttpClientEngine> { OkHttp.create() }
    single<HttpClientConfig<OkHttpConfig>> { HttpClientConfig() }
}

@Test
fun checkKtorModule() {
    ktorModule.verify()
}