Android Testing

Introduction

This, currently, is a minimum example of testing

Environment

Had a ton of problems trying to get this to work. Using the default for a project did not work. The test below using Retrofit and RxJava3.

    implementation 'io.reactivex.rxjava3:rxandroid:3.0.0'
    implementation 'io.reactivex.rxjava3:rxjava:3.0.13'

    implementation 'com.squareup.retrofit2:retrofit:2.9.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.9.0'
    implementation 'com.squareup.retrofit2:adapter-rxjava3:2.9.0'

    testImplementation 'junit:junit:4.13.2'
    testImplementation 'org.mockito:mockito-inline:4.3.1'

Code to test

So this is the example I was testing.

    private fun fetchCountries() {
        loading.value = true
        disposable.add(
            countriesService.getCountries()
                // Create new Thread
                .subscribeOn(Schedulers.newThread())
                // Provide Thread to received Response
                .observeOn(AndroidSchedulers.mainThread())
                // What to do with it
                .subscribeWith(object: DisposableSingleObserver<List<Country>>() {

                    // RxJava Success
                    override fun onSuccess(value: List<Country>?) {
                        Timber.d("All Good")
                        countries.value = value
                        countryLoadError.value = false
                        loading.value = false
                    }
                    // RxJava error
                    override fun onError(e: Throwable) {
                        Timber.d("All bad")
                        countryLoadError.value = true
                        loading.value = false
                    }
                })
        )
    }

The CountriesService is injected with Dagger2 and uses Retrofit to call an API call.

class CountriesService {
    @Inject
    lateinit var api: CountriesApi

    init {
        DaggerApiComponent.create().inject(this)
    }

    fun getCountries(): Single<List<Country>> = api.getCountries()
}