Can't make Realm test with a listener to run

I'm currently trying to run an instrumented test of Realm with a listener. I'm pretty new to Android and have read the minimal Realm documentation and SO questions but really can't figure this out.

I have this realm test class that I subclass for future use

open class RealmInstrumentedUnitTest {

    lateinit var mockRealm: Realm

    @Before
    fun setup() {
        Looper.prepare()
        val testConfig = RealmConfiguration.Builder().inMemory().name("test-realm").build()
        Realm.setDefaultConfiguration(testConfig)
        this.mockRealm = Realm.getDefaultInstance()
    }

    @After
    @Throws(Exception::class)
    public fun tearDown() {
        Looper.loop()
        this.mockRealm.close()
    }
}

Then I subclass the preceding and implement a test:

@Test
fun testOverlappingSessionDeletion() {

val realm = this.mockRealm
this.sessions = realm.where(Session::class.java).findAll() // monitor session deletions

this.sessions?.addChangeListener { t, changeSet ->

    val deletedSessions = realm.where(Session::class.java).`in`("id", changeSet.deletions.toTypedArray()).findAll()
    deletedSessions.forEach { it.cleanup() }

}

• I can't figure how to configure the looper to make it run
• In this configuration I get "Test failed to run to completion. Reason: 'Instrumentation run failed due to 'Process crashed.'."
• If I put the Looper.loop() earlier I get a never ending loop

How should I configure this to run it properly?

Thank you so much