Mock of RealmResults example.

RealmTestHelper.kt

package com.github.kazukinr.sample.realm.data

import com.nhaarman.mockito_kotlin.any
import com.nhaarman.mockito_kotlin.mock
import com.nhaarman.mockito_kotlin.whenever
import io.reactivex.Flowable
import io.realm.RealmObject
import io.realm.RealmResults

object RealmTestHelper {

    inline fun <reified E : RealmObject> mockResults(data: List<E>): RealmResults<E> {
        val realmResults = mock<RealmResults<E>>()

        whenever(realmResults.isEmpty()).thenReturn(data.isEmpty())
        whenever(realmResults.isLoaded()).thenReturn(true)
        whenever(realmResults.isValid()).thenReturn(true)
        whenever(realmResults.isManaged()).thenReturn(true)

        whenever(realmResults.size).thenReturn(data.size)

        whenever(realmResults.first()).thenReturn(data[0])
        whenever(realmResults.first(any<E>())).thenAnswer { invocation ->
            if (data.isNotEmpty()) {
                data[0]
            } else {
                invocation.arguments[0]
            }
        }
        whenever(realmResults.get(any<Int>())).thenAnswer { invocation ->
            val index = invocation.arguments[0] as Int
            data[index]
        }
        whenever(realmResults.iterator()).thenReturn(data.toMutableList().iterator())

        whenever(realmResults.asFlowable()).thenReturn(Flowable.fromCallable {
            realmResults
        })

        return realmResults
    }
}