InstrumentationTestでRxIdlerを使おうとしたがダメだった ref: http://qiita.com/kubode/items/7cfc0767dcc560498725

build.gradle

android {
    buildTypes {
        release {
            multiDexKeepProguard 'multidex-config.pro'
            ...
        }
    }
}

file0.txt

'com.android.tools.build:gradle:3.0.0'
'com.android.support.test.espresso:espresso-core:3.0.1'
'com.android.support.test:runner:1.0.1'
'com.squareup.rx.idler:rx1-idler:0.9.0'

file1.txt

class MyTestRunner : AndroidJUnitRunner() {
    override fun onStart() {
        RxJavaPlugins.getInstance().registerSchedulersHook(RxIdler.hooks())
        super.onStart()
    }
}

multidex-config.pro

-keep class rx.functions.Action0
-keep class rx.plugins.RxJavaPlugins
-keep class com.squareup.rx.idler.RxIdler