Kotlin Mockito Rx Callback

MockitoKotlinHelpers.kt

/**
 * Helper functions that are workarounds to kotlin Runtime Exceptions when using kotlin.
 */

import org.mockito.ArgumentCaptor
import org.mockito.Mockito

/**
 * Returns Mockito.eq() as nullable type to avoid java.lang.IllegalStateException when
 * null is returned.
 *
 * Generic T is nullable because implicitly bounded by Any?.
 */
fun <T> eq(obj: T): T = Mockito.eq<T>(obj)


/**
 * Returns Mockito.any() as nullable type to avoid java.lang.IllegalStateException when
 * null is returned.
 */
fun <T> any(): T = Mockito.any<T>()


/**
 * Returns ArgumentCaptor.capture() as nullable type to avoid java.lang.IllegalStateException
 * when null is returned.
 */
fun <T> capture(argumentCaptor: ArgumentCaptor<T>): T = argumentCaptor.capture()


/**
 * Helper function for creating an argumentCaptor in kotlin.
 */
inline fun <reified T : Any> argumentCaptor(): ArgumentCaptor<T> =
        ArgumentCaptor.forClass(T::class.java)

inline fun <reified T : Any> mockInline() = Mockito.mock(T::class.java)

Plain.kt

val callback = object : SnapshotCallback<SnapshotResponse> {
    override fun success(data: SnapshotResponse?) {
        if (data != null) {
            view.setSnapshot(data)
        }
        view.hideProgress()
    }

    override fun error(error: SnapshotError) {
        view.hideProgress()
        view.showError()
    }
}

Rx-y.kt

lateinit var callback: SnapshotCallback<SnapshotResponse>
Single.create { emitter: SingleEmitter<SnapshotResponse> ->
    callback = object : SnapshotCallback<SnapshotResponse> {
        override fun success(data: SnapshotResponse?) {
            data?.let { emitter.onSuccess(data) }
        }

        override fun error(error: SnapshotError) {
            emitter.onError(error)
        }
    }
}.observeOn(ioScheduler)
        .subscribeOn(uiScheduler)
        .doOnSuccess { result ->
            view.hideProgress()
            view.setSnapshot(result)
        }
        .doOnError {
            view.hideProgress()
            view.showError()
        }
        .subscribe()