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How to test Retrofit API call using MockWebServer

I have a class that creates the RetrofitInstance in a very basic way, and I want to test that it is working correctly by running a dummy api against a mockedWebServer but for some reason Instead of getting a succesfull 200 response I get a 0.
fun createRetrofitInstance(baseUrl: String, client: OkHttpClient): Retrofit {
return Retrofit.Builder().baseUrl(baseUrl)
.addCallAdapterFactory(callAdapterFactory)
.addConverterFactory(converterFactory)
.client(client)
.build()
}
and I want to test it using a DummyApi
#Test
fun `should return successful response`() {
val mockedWebServer = MockWebServer()
val mockedResponse = MockResponse().setResponseCode(200)
mockedWebServer.enqueue(mockedResponse)
mockedWebServer.start()
mockedWebServer.url("/")
val retrofit = tested.createRetrofitInstance(mockedWebServer.url("/").toString(), client)
val testApi = retrofit.create(TestApi::class.java)
val actualResponseCall: Call<Any> = testApi.getTestApi()
assertEquals(200, actualResponseCall.execute().code())
mockedWebServer.shutdown()
}
DummyApi
interface TestApi {
#GET("/")
fun getTestApi() : Call<Any>
}

You should read through one of the excellent tutorials on MockWebServer out there. Too much information for just this answer. I think in this case you are just missing the setBody call.
https://medium.com/android-news/unit-test-api-calls-with-mockwebserver-d4fab11de847
val mockedResponse = MockResponse()
mockedResponse.setResponseCode(200)
mockedResponse.setBody("{}") // sample JSON

How to check if a server is reachable with retrofit in kotlin?

I have a basic retrofit setup in kotlin.
val BASE_URL: String = "http://10.0.2.2:5000/"
private val moshi = Moshi.Builder()
.add(KotlinJsonAdapterFactory())
.build()
private val interceptor: HttpLoggingInterceptor = HttpLoggingInterceptor().apply {
this.level = HttpLoggingInterceptor.Level.BODY
}
private val client: OkHttpClient = OkHttpClient.Builder().apply {
this.addInterceptor(interceptor)
}.build()
private val retrofit = Retrofit.Builder()
.addConverterFactory(MoshiConverterFactory.create(moshi))
.baseUrl(BASE_URL)
.client(client)
.build()
val service: Api by lazy {
retrofit.create(Api::class.java)
}
I want to check if the server I'm fetching my data from is running - if its not I want to fall back on the local DB for basic functionality. I tried something similar at first but there's a couple of things that are wrong with this approach. First of all the request timeout period is 10 seconds long, which is a little bit more than you'd want it to be for an app. Second, well, it doesn't really work, it'll still throw an exception if the server is offline.
fun serverReachable(): Boolean {
return try {
GlobalScope.async {
// call whatever api function here
}
true
} catch (e: Exception) {
false
}
}
Is there are quick and dirty version of checking if the server is up?

Kotlin : Okhttpclient correct way of creating single instance? OkHttpClient doesn't go through server ip check?

I'm new at android kotlin development and currently trying to solve how to correctly create a single instance of OkHttpClient for app-wide usage. I've currently sort-of* created a single instance of client and using it to communicate with the server, however currently the back-end server is not using token/userid for validation but IP check. I can log in the user no problem, but after going to another activity trying to call api, I'm being blocked access by server because apparently IP is not the same. I've used POSTMAN as well as already created a same functioning iOS app that is working with no issue. So my question is am i creating the single instance of OkHttpClient wrong? Or is OkHttpClient not suitable for this kind of ipcheck system? Should i use other library, and if yes, any suggestion and examples?
Thanks in advance
Currently i tried creating it like this :
class MyApplication: Application(){
companion object{
lateinit var client: OkHttpClient
}
override fun onCreate(){
super.onCreate()
client = OkHttpClient()
}
}
Then i created a helper class for it :
class OkHttpRequest {
private var client : OkHttpClient = MyApplication.client
fun POST(url: String, parameters: HashMap<String, String>, callback: Callback): Call {
val builder = FormBody.Builder()
val it = parameters.entries.iterator()
while (it.hasNext()) {
val pair = it.next() as Map.Entry<*, *>
builder.add(pair.key.toString(), pair.value.toString())
}
val formBody = builder.build()
val request = Request.Builder()
.url(url)
.post(formBody)
.build()
val call = client.newCall(request)
call.enqueue(callback)
return call
}
fun GET(url: String, callback: Callback): Call {
val request = Request.Builder()
.url(url)
.build()
val call = client.newCall(request)
call.enqueue(callback)
return call
}
}
Finally I'm using it like this :
val loginUrl = MyApplication.postLoginUrl
var userIdValue = user_id_textfield.text.toString()
var passwordValue = password_textfield.text.toString()
val map: HashMap<String, String> = hashMapOf("email" to userIdValue, "password" to passwordValue)
var request = OkHttpRequest()
request.POST(loginUrl, map, object : Callback {
val responseData = response.body?.string()
// do something with response Data
}
And on another activity after user log in :
val getPaidTo = MyApplication.getPaidTo
var request = OkHttpRequest()
request.GET(getPaidTo, object: Callback{
//do something with data
}

First, don't use your OkHttpClient directly in every Activity or Fragment, use DI and move all of your business logic into Repository or some source of data.
Here I will share some easy way to make REST request with Retrofit, OkHttpClient and Koin, if you want use the same:
WebServiceModule:
val webServiceModule = module {
//Create HttpLoggingInterceptor
single { createLoggingInterceptor() }
//Create OkHttpClient
single { createOkHttpClient(get()) }
//Create WebServiceApi
single { createWebServiceApi(get()) }
}
/**
* Setup a Retrofit.Builder and create a WebServiceApi instance which will hold all HTTP requests
*
* #okHttpClient Factory for HTTP calls
*/
private fun createWebServiceApi(okHttpClient: OkHttpClient): WebServiceApi {
val retrofit = Retrofit.Builder()
.baseUrl(BuildConfig.REST_SERVICE_BASE_URL)
.client(okHttpClient)
.addCallAdapterFactory(CoroutineCallAdapterFactory())
.build()
return retrofit.create(WebServiceApi::class.java)
}
/**
* Create a OkHttpClient which is used to send HTTP requests and read their responses.
*
* #loggingInterceptor logging interceptor
*/
private fun createOkHttpClient(
loggingInterceptor: HttpLoggingInterceptor
): OkHttpClient {
return OkHttpClient.Builder()
.addInterceptor(loggingInterceptor)
.readTimeout(defaultTimeout, TimeUnit.SECONDS)
.connectTimeout(defaultTimeout, TimeUnit.SECONDS)
.build()
}
And now you can inject your WebServiceApi everywhere, but better inject it in your Repository and then use it from some ViewModel
ViewModelModule:
val viewModelModule = module {
//Create an instance of MyRepository
single { MyRepository(webServiceApi = get()) }
}
Hope this help somehow

Okay, after i check with the back-end developer, i figured out the problem wasn't the ip address(it stays the same) but that the cookie was not saved by okhttp, both POSTMan and xcode automatically save the token returned into cookie so i never noticed that was the problem. So after googling a-bit, the solution can be as easy as this:
class MyApplication : Application(){
override fun onCreate(){
val cookieJar = PersistentCookieJar(SetCookieCache(),SharedPrefsCookiePersistor(this))
client = OkHttpClient.Builder()
.cookieJar(cookieJar)
.build()
}
}
With adding persistentCookieJar to gradle.

Dynamic urls with Koin ans Retrofit

Using Retrofit for network calls and Koin for dependency injection in an Android app, how to support dynamic url change?
(while using the app, users can switch to another server)
EDIT: network module is declared like this:
fun networkModule(baseUrl: String) = module {
single<Api> {
Retrofit.Builder()
.baseUrl(baseUrl)
.client(OkHttpClient.Builder().readTimeout(30, TimeUnit.SECONDS)
.connectTimeout(30, TimeUnit.SECONDS)
.writeTimeout(30, TimeUnit.SECONDS)
.build())
.build().create(Api::class.java)
}
I am starting Koin in the Aplication class onCreate like this:
startKoin {
if (BuildConfig.DEBUG) AndroidLogger() else EmptyLogger()
androidContext(this#App)
modules(listOf(networkModule(TEST_API_BASE_URL), storageModule, integrationsModule, appModule))
}

I faced the same problem recently. The most convenient way is to use a Interceptor to change the baseUrl dynamically.
class HostSelectionInterceptor(defaultHost: String? = null, defaultPort: Int? = null) : Interceptor {
#Volatile var host: String? = null
#Volatile var port: Int? = null
init {
host = defaultHost
port = defaultPort
}
#Throws(IOException::class)
override fun intercept(chain: Interceptor.Chain): okhttp3.Response {
var request = chain.request()
this.host?.let {host->
val urlBuilder = request.url().newBuilder()
urlBuilder.host(host)
this.port?.let {
urlBuilder.port(it)
}
request = request.newBuilder().url(urlBuilder.build()).build()
}
return chain.proceed(request)
}
}
Initialize it with your default url.
single { HostSelectionInterceptor(HttpUrl.parse(AppModuleProperties.baseUrl)?.host()) }
single { createOkHttpClient(interceptors = listOf(get<HostSelectionInterceptor>()))}
And add this interceptor when creating your OkHttpClient.
val builder = OkHttpClient().newBuilder()
interceptors?.forEach { builder.addInterceptor(it) }
To change the url you only have to update the interceptors member.
fun baseUrlChanged(baseUrl: String) {
val hostSelectionInterceptor = get<HostSelectionInterceptor>()
hostSelectionInterceptor.host = baseUrl
}

I've tried with Koin loading/unloading modules..and for a short period of time it worked, but later, after a minimal change I wasn't able to make it reload again.
At the end, I solved it with wrapper object:
class DynamicRetrofit(private val gson: Gson) {
private fun buildClient() = OkHttpClient.Builder()
.build()
private var baseUrl = "https://etc..." //default url
private fun buildApi() = Retrofit.Builder()
.baseUrl(baseUrl)
.addConverterFactory(GsonConverterFactory.create(gson))
.client(buildClient())
.build().create(MyApi::class.java)
var api: MyApi = buildApi()
private set
fun setUrl(url: String) {
if (baseUrl != url)
baseUrl = url
api = buildApi()
}}
I declare it in within Koin module like this:
single<DynamicRetrofit>()
{
DynamicRetrofit(get(), get())
}
and use it in pretty standard way:
dynamicRetrofit.api.makeSomeRequest()
It was good solution for my case since I change baseUrl very rarely. If you need to make often and parallel calls to two different servers it will probably be inefficient since you this will recreate HTTP client often.

Is it possible to create different instances of the same object and access them by passing parameters to get() function in Koin?

I am using Koin as a DI for my app. I created a module:
object NetworkModule {
fun get() = module {
single {
val authenticationInterceptor = Interceptor { chain ->
// Request customization goes here
}
OkHttpClient.Builder()
.connectTimeout(15, TimeUnit.SECONDS)
.readTimeout(60, TimeUnit.SECONDS)
.writeTimeout(60, TimeUnit.SECONDS)
.addInterceptor(authenticationInterceptor) //Not all clients might have this interceptor
.build()
}
single {
Retrofit.Builder()
.baseUrl("example.com")
.client(get(/* I would like to send some paramter here */))
.addConverterFactory(GsonConverterFactory.create(get()))
.addCallAdapterFactory(RxJava2CallAdapterFactory.create())
.build()
.create(Api::class.java)
}
}
}
How can I create different HttpClient or Retrofit instances which have different parameters set or has different instantiation? For instance, in some cases, I might need OkHttpClient with AutheniticationInterceptor and in some other cases my client might not need to use it.
Can I pass some parameters when calling get() so that I can get different instances? Any suggestions would be apprieciated.

You can use named properties - e.g.
single<OkHttpClient>(named("auth")){
// here you pass the version with authinterceptor
}
single<OkHttpClient>(named("noAuth")){
// here you pass the version without authinterceptor
}
Then in your get() method you pass the name, e.g.
.client(get(named("auth")))

You can do like below (Use koin latest version for named property).Also why I use single and factory because
single— declare a singleton definition of given type. Koin keeps only one instance of this definition
factory — declare a factory definition of given type. Koin gives a new
instance each time
const val WITH_AUTH: String = "WITH_AUTH"
const val WITH_OUT_AUTH: String = "WITH_OUT_AUTH"
val remoteModule = module {
factory(named("HEADERS")) {
val map = it.get<MutableMap<String, String>>(0)
Interceptor { chain ->
val original = chain.request()
val request = original.newBuilder()
map.forEach { entry ->
request.addHeader(entry.key, entry.value)
}
chain.proceed(request.build())
}
}
factory(named("auth")) {
OkHttpClient.Builder().apply {
map["AUTHORIZATION"] = "token"
readTimeout(1, TimeUnit.MINUTES)
connectTimeout(2, TimeUnit.MINUTES)
writeTimeout(1, TimeUnit.MINUTES)
addInterceptor(get(named("HEADERS"), parameters = {
parametersOf(map)
}))
}.build()
}
factory(named("auth")) {
Retrofit.Builder()
.baseUrl("base_url")
.client(get(named("auth")))
//.addCallAdapterFactory()
.addConverterFactory(GsonConverterFactory.create())
.build()
.create(ApiService::class.java)
}
single(named("noAuth")) {
val map = mutableMapOf(ACCEPT to CONTENT_TYPE)
OkHttpClient.Builder().apply {
readTimeout(1, TimeUnit.MINUTES)
connectTimeout(2, TimeUnit.MINUTES)
writeTimeout(1, TimeUnit.MINUTES)
addInterceptor(get(named("HEADERS"), parameters = {
parametersOf(map)
}))
}.build()
}
single(named("noAuth")) {
Retrofit.Builder()
.baseUrl("base_url")
.client(get(named("noAuth")))
//.addCallAdapterFactory()
.addConverterFactory(GsonConverterFactory.create())
.build()
.create(ApiService::class.java)
}
}
Now in your activity or viewModel
protected val apiServiceWithoutHeader: ApiService by inject(named(WITH_OUT_HEADER))
protected val apiServiceWithHeader: ApiService by inject(named(WITH_HEADER))
with above object call appropriate API