How to write proper test for reactive interface repository which returns Observable only when there is some event, how to mock triggering that event - unit-testing

Question

I am trying to write proper test for my reactive repository, which just listen for location changes. I don't want to actually listen for location changes and just 'invoke' new location change multiple times with just created custom Location.
Here is the repository and its function for gathering locations:
interface RxLocationRepository {
#SuppressLint("MissingPermission")
fun onLocationUpdate(): Observable<Location>
fun stopLocationUpdates()
}
Here is the implementation of it, which actually DON'T MATTER because i don't want to listen for real location updates, but i want to show you that it is just reactive implementation for listen to LocationManager updates:
class LocationNativeRepository(
val locationManager: LocationManager,
val geoEventsDistanceMeters: Int,
val geoEventsIntervalSeconds: Int) : RxLocationRepository{
var locationToPopulate: Location = Location(LocationManager.GPS_PROVIDER)
lateinit var mLocationCallbackNativeApi: LocationListener
private val subject: BehaviorSubject<Location> = BehaviorSubject.createDefault(locationToPopulate)
var locationEmitter: Observable<Location> = subject.hide()
init {
configureNativeLocationEmitter()
}
override fun onLocationUpdate(): Observable<Location> {
return locationEmitter
}
#SuppressLint("MissingPermission")
override fun stopLocationUpdates() {
locationManager.removeUpdates(mLocationCallbackNativeApi)
}
#SuppressLint("MissingPermission")
private fun configureNativeLocationEmitter() {
mLocationCallbackNativeApi = object : LocationListener {
override fun onLocationChanged(location: Location) {
subject.onNext(location)
}
override fun onStatusChanged(provider: String, status: Int, extras: Bundle) {}
override fun onProviderEnabled(provider: String) {}
override fun onProviderDisabled(provider: String) {}
}
try {
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,
(geoEventsIntervalSeconds * 1000).toLong(),
geoEventsDistanceMeters.toFloat(),
mLocationCallbackNativeApi,
Looper.getMainLooper())
} catch (ignored: IllegalArgumentException) {
ignored.printStackTrace()
}
try {
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,
(geoEventsIntervalSeconds * 1000).toLong(),
geoEventsDistanceMeters.toFloat(),
mLocationCallbackNativeApi,
Looper.getMainLooper())
} catch (ignored: IllegalArgumentException) {
ignored.printStackTrace()
}
}
}
So how i can invoke this repository in my test to actually trigger the onLocationUpdate() method? So for example i will make it emit 3 times location like this:
val location = Location("test").apply {
latitude = 1.234
longitude = 5.678
accuracy = 20f
time = Date().time
}

Answer 1

Create a PublishSubject<Location> variable. Create an anonymous sub-class of RxLocationRepository, where the onLocationUpdate() method returns the variable. Then emit values into the variable to provide new locations.