Unit Testing With Koin Isolated Context

[Ynnck123]

Hi,

when using Koin Isolated Context like the Koin documentation suggests:

// Get a Context for your Koin instance
object MyIsolatedKoinContext {

    val koinApp = koinApplication {
        // declare used modules
        modules(coffeeAppModule)
    }

    val koin = koinApp.koin 
}

How would you overwrite the koinApp in your unit tests to switch declarations? I am currently running into the problem that I am not able to use different implementations in my unit tests because I can only fill the default Koin context from my understanding and have no option to switch out this isolated context.

Do you have any suggestions?

Edit: I am using field injection via overwritten getKoin() from the KoinComponent function that uses my isolated context

[ragboyjr]

Not sure when these docs were added, but they talk about this here: https://github.com/InsertKoinIO/koin/discussions?discussions_q=is%3Aopen+

Personally, I also use a similar approach to just explicitly overriding services via the MyIsolatedKoinContext.koin instance.

[tezov]

If you don't declare your module in your context like this,

object KoinContext {
    lateinit var koinApplication: KoinApplication

    val koin get() = koinApplication.koin
}

Then somewhere else :

    fun startMyIsolatedKoin() = koinApplication {
            
           what ever modules you need

        }.also { KoinContext.koinApplication = it }
        

Then when you test :

    @BeforeTest
    fun setup() {
        processActionUseCase = mock()

        // minimal injection need for this test
        KoinContext.koinApplication = koinApplication {
            modules(
                module {
                    single<ProcessActionUseCase> { processActionUseCase }
                }
            )
        }
      ....

        sut = FormSendUrlActionMiddleware(
            useCaseExecutor = useCaseExecutor,
            ...
        )

It will work either you inject with constructor or implement with your KoinComponent.

interface KoinComponent : org.koin.core.component.KoinComponent {
    override fun getKoin(): Koin = KoinContext.koin
}

PS: Works also with scope ;)

Best regards.