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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

Twitter oauth/request_token 200 code with empty response body

I'm implementing Twitter OAuth flows as per:
https://developer.twitter.com/en/docs/authentication/guides/log-in-with-twitter
I am getting a response back for the first step (oauth/request_token) which has a 200 code, but the response body is completely empty.
I'm using Retrofit to call the API, and have hooked up an interceptor OkHttpClient to debug the response like so:
val client = OkHttpClient.Builder().also { builder ->
builder.addInterceptor { chain ->
val request = chain.request()
val response = chain.proceed(request)
response
}
}.build()
Then setting up Retrofit like so:
Retrofit.Builder()
.baseUrl(TWITTER_AUTH_BASE_URL)
.addConverterFactory(GsonConverterFactory.create())
.client(client)
.build()
.create(TwitterAuthRetrofit::class.java)
.getRequestToken(
authorizationHeaders
).enqueue(object : Callback<TwitterRequestToken> {
override fun onResponse(call: Call<TwitterRequestToken>, response: Response<TwitterRequestToken>) {
onSuccess(response.body())
}
override fun onFailure(call: Call<TwitterRequestToken>, t: Throwable) {
onFailure()
}
})
When I debug in the interceptor, I can see the response is successful (200) but the response body is empty, which I think is causing my Gson deserialization to fail.
The result of calling response.body.contentLength() in the interceptor is -1.
The result of calling response.code in the interceptor is 200.
Here is the model I am attempting to deserialize the response body to:
data class TwitterRequestToken(
#SerializedName(value = "oauth_token")
val token: String,
#SerializedName(value = "oauth_token_secret")
val tokenSecret: String,
#SerializedName(value = "oauth_callback_confirmed")
val callbackConfirmed: Boolean
)
Note I am using #SerializedName to provide the keys for the response body, whilst the names of my properties are arbitrary to our app (we use camel case). I add a GsonConverterFactory to the Retrofit instance using the builder and have done this in the same way for many other requests before with no issues.
Here is the response I am getting from the API, which I am looking at via debugging in the interceptor above:
Response{protocol=h2, code=200, message=, url=https://api.twitter.com/oauth/request_token}
And here is the cause message from the Throwable I am getting in the onFailure callback from Retrofit:
com.google.gson.stream.MalformedJsonException:
Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 1 path $
Has anyone got any idea what might cause this?

Finally figured it out, hope this helps someone in future...
The response body from the Twitter API for oauth/request_token isn't encoded as JSON; you will need to read it from the response buffer. Specifically, when implementing the API with Retrofit, you will want your Retrofit interface to return ResponseBody (rather than your custom class), remove GSON from the Retrofit builder and, in the onResponseCallback from Retrofit, write the following code to read the buffer to a string, then split the string on & to get each key val pair, then you can split each of these on = and make sure you have all 3 values before constructing your model:
override fun onResponse(call: Call<ResponseBody>, response: Response<ResponseBody>) {
response.body()?.also { body ->
body.source().readString(Charsets.UTF_8).split('&').map { param ->
param.split('=').let { keyVal ->
keyVal[0] to keyVal[1]
}
}.toMap().let { paramMap ->
val oauthToken = paramMap["oauth_token"]
val oauthTokenSecret = paramMap["oauth_token_secret"]
val oauthCallbackConfirmed = paramMap["oauth_callback_confirmed"]?.toBoolean()
if (oauthToken == null || oauthTokenSecret == null || oauthCallbackConfirmed == null) {
onFailure()
} else {
onSuccess(
TwitterRequestToken(
oauthToken,
oauthTokenSecret,
oauthCallbackConfirmed
)
)
}
}
} ?: onFailure()
}

Retrofit doesn't send POST request

I can't seem to get the POST request working with Retrofit. My code:
ApiService.kt contains a function
#Headers("Content-Type: application/json")
#POST("resume")
suspend fun resumeAsync(#Body request: JSONObject): Response<String>
Then in my ListViewModel.kt I have a function
fun resume(id: String) {
coroutineScope.launch {
try {
val paramObject = JSONObject()
paramObject.put("id", id)
val response = Api.retrofitService.resumeAsync(paramObject)
if (response.isSuccessful) {
_status.value = "Success: Resumed!"
}
} catch (e: Exception) {
_status.value = "Failure: " + e.message
}
}
}
Why is this not working? I don't get any error or response back. If I put Log.i in the Api or the view model it says it's triggered
By debugging I found out this error:
2020-09-15 11:40:10.904 20622-20622/com.example.app I/NETWORK: Unable to create #Body converter for class org.json.JSONObject (parameter #1) for method ApiService.resumeAsync
I am using Moshi as well
private val moshi = Moshi.Builder()
.add(KotlinJsonAdapterFactory())
.build()
private val retrofit = Retrofit.Builder()
.addConverterFactory(MoshiConverterFactory.create(moshi))
.baseUrl(BASE_URL)
.build()

You can try adding a logging interceptor to your okHttp client and check what you're sending and receiving in the request.
val logging = HttpLoggingInterceptor()
logging.setLevel(HttpLoggingInterceptor.Level.BODY)
Is the url/endpoint correct?
Are you missing a "/" at the end of the url?
Have you declared internet permission in the manifest?
etc.
Solution:
Wrapping request body:
#Body body: RequestBody
val body = RequestBody.create(MediaType.parse("application/json"), obj.toString())

If you need to receive raw json then use Call<*>
#Headers("Content-Type: application/json")
#POST("resume")
fun resumeAsync(#Body request: JSONObject): retrofit2.Call<String>
Inside coroutine (without suspend keyword above)
// or .awaitResponse() to get Response<*> object
val response = Api.retrofitService.resumeAsync(paramObject).await()

Can you debug on this line
if (response.isSuccessful) {
try to check the variable response;
Or you shoud check whether the server is work, check it with other tools like Postman

So I solved my problem by doing what #Paul Nitu recommended
val body = RequestBody.create(MediaType.parse("application/json"), obj.toString())

Retrofit2 authentication error to IBM's Speech to Text

I am trying to access IBM's Speech to Text service without using the library. I am using Retrofit with GSON.
The issue is in the authentication, which apparently does not occur correctly, returning code 401. From the official documentation, the HTTP request should come in this format
curl -X POST -u "apikey:{apikey}" \
--header "Content-Type: audio/flac" \
--data-binary #{path_to_file}audio-file.flac \
"{url}/v1/recognize"
When I test the curl command with my credentials, the service works fine.
This is the interface I'm using
interface SpeechToTextApi {
#Multipart
#POST("v1/recognize")
fun speechToText(
#Header("Authorization") authKey: String,
#Part("file") filename: RequestBody,
#Part voiceFile: MultipartBody.Part
): Call<List<SpeechToText>>
}
where I have the following data classes
data class SpeechToText(val results: List<SttResult>)
data class SttResult(val alternatives: List<RecognitionResult>, val final: Boolean)
data class RecognitionResult(val confidence: Float, val transcript: String)
and this is how I set up Retrofit
private val retrofit = Retrofit.Builder()
.baseUrl(STT_BASE_URL)
.addConverterFactory(GsonConverterFactory.create())
.build()
private val service = retrofit.create(SpeechToTextApi::class.java)
while calling the actual service looks like this
val requestFile = RequestBody.create(MediaType.parse("audio/mp3"), file.name)
val body = MultipartBody.Part.createFormData("file", file.name, requestFile)
service
.speechToText(getString(R.string.stt_iam_api_key), requestFile, body)
.enqueue(object: Callback<List<SpeechToText>> {
override fun onResponse(call: Call<List<SpeechToText>>, response: Response<List<SpeechToText>>) {
val listOfStts = response.body()
Log.d(TAG, "Response code: ${response.code()}")
if (listOfStts != null) {
for (stt in listOfStts) {
for (res in stt.results) {
Log.d(TAG, "Final value: ${res.final}")
for (alt in res.alternatives) {
Log.d(TAG, "Alternative confidence: ${alt.confidence}\nTranscript: ${alt.transcript}")
Toast.makeText(this#MainActivity, alt.transcript, Toast.LENGTH_SHORT).show()
}
}
}
}
}
override fun onFailure(call: Call<List<SpeechToText>>, t: Throwable) {
Log.d(TAG, "Error: ${t.message}")
t.printStackTrace()
}
})
Recordings are MP3 files, for which I am sure they are stored correctly and accessible. I have replaced audio/flac with audio/mp3 as well.
Issue seems to be in the way authentication works. Prior to the code I have shown above, I've used
private val retrofit = Retrofit.Builder()
.baseUrl(STT_BASE_URL)
.addConverterFactory(GsonConverterFactory.create())
.client(OkHttpClient.Builder()
.addInterceptor { chain ->
val request = chain.request()
val headers = request
.headers()
.newBuilder()
.add("Authorization", getString(R.string.stt_iam_api_key))
.build()
val finalRequest = request.newBuilder().headers(headers).build()
chain.proceed(finalRequest)
}
.build())
.build()
but the same response code 401 persisted. Of course, the interface method lacked the #Header parameter.
Any sort of help is much appreciated.

I am kind of saddened by the fact nobody was able to solve this one sooner, but here's the solution I came across by accident when working on a different project altogether.
As you can see from the curl command, authentication comes in the form of username: password pattern, in this case, username being apikey string and password is your API key.
So the way you should tackle this is by building your Retrofit instance this way:
fun init(token: String) {
//Set logging interceptor to BODY and redact Authorization header
interceptor.level = HttpLoggingInterceptor.Level.BODY
interceptor.redactHeader("Authorization")
//Build OkHttp client with logging and token interceptors
val okhttp = OkHttpClient().newBuilder()
.addInterceptor(interceptor)
.addInterceptor(TokenInterceptor(token))
.build()
//Set field naming policy for Gson
val gsonBuilder = GsonBuilder()
gsonBuilder.setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
//Build Retrofit instance
retrofit = Retrofit.Builder()
.baseUrl(IBM_BASE_URL)
.addConverterFactory(GsonConverterFactory.create(gsonBuilder.create()))
.client(okhttp)
.build()
}
and create this custom interceptor
class TokenInterceptor constructor(private val token: String) : Interceptor {
override fun intercept(chain: Interceptor.Chain): Response {
val original = chain.request()
val requestBuilder = original
.newBuilder()
.addHeader("Authorization", Credentials.basic("apikey", token))
.url(original.url)
return chain.proceed(requestBuilder.build())
}
}
You need to use Credentials.basic() in order to encode credentials.
I really hope somebody with a similar issue stumbles across this and saves themselves some time.

Singleton that will hold an instance of Retrofit

So I have created a login that will take an username and password input from the user, encode it with Base64 in order to create a token in the format: ("Authorization", AUTH) where AUTH = "Basic " + Base64 encoding of user and password. This is sent via Headers.
So, in the end, it looks like this: Authorization: Basic XXXXXX, where XXXXXX is the user token.
And then it will check whether or not that user exists in the database via an API request.
I am using Retrofit and OkHttp3 in the same class as RetrofitClient and this class is responsible for using the API and adding those Headers.
Later, I use the RetrofitClient class on the Login Activity.
What I need to do now, is make this "token" available to all the other activities by creating a Singleton that will store the data of the Retrofit after a successful login. But I do not know how to do this.
I started learning Kotlin and Android 3 weeks ago.
Here is my code:
GET_LOGIN.kt
interface GET_LOGIN {
#GET("login")
fun getAccessToken() : Call<String>
}
RetrofitClient.kt
class RetrofitClient {
fun login(username:String, password:String){
val credentials = username + ":" + password
val AUTH = "Basic " + Base64.encodeToString(credentials.toByteArray(Charsets.UTF_8), Base64.DEFAULT).trim()
retrofit = init(AUTH)
}
// Initializing Retrofit
fun init(AUTH: String) : Retrofit{
// Creating the instance of an Interceptor
val logging = HttpLoggingInterceptor()
logging.level = HttpLoggingInterceptor.Level.BODY
// Creating the OkHttp Builder
val client = OkHttpClient().newBuilder()
// Creating the custom Interceptor with Headers
val interceptor = Interceptor { chain ->
val request = chain?.request()?.newBuilder()?.addHeader("Authorization", AUTH)?.build()
chain?.proceed(request)
}
client.addInterceptor(interceptor) // Attaching the Interceptor
//client.addInterceptor(logging) // Attaching the Interceptor
// Creating the instance of a Builder
val retrofit = Retrofit.Builder()
.baseUrl("https://srodki.herokuapp.com/") // The API server
.client(client.build()) // Adding Http Client
.addConverterFactory(GsonConverterFactory.create()) // Object Converter
.build()
return retrofit
}
lateinit var retrofit : Retrofit
fun providesGetLogin(): GET_LOGIN = retrofit.create(GET_LOGIN::class.java)
}
LoginActivity.kt
var RetrofitClient : RetrofitClient = RetrofitClient()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_login)
loginBtn.setOnClickListener {
val user = userTxt.text.toString()
val pass = passTxt.text.toString()
if (validateLogin(user, pass)){
login(user, pass)
}
}
}
fun validateLogin(user: String, pass: String): Boolean {
if (user == null || user.trim().isEmpty()){
Toast.makeText(this, "Missing Username or Password", Toast.LENGTH_SHORT).show()
return false
}
if (pass == null || pass.trim().isEmpty()){
Toast.makeText(this, "Missing Username or Password", Toast.LENGTH_SHORT).show()
return false
}
return true
}
fun login(user: String, pass: String) {
RetrofitClient.login(user, pass)
val apiLogin = RetrofitClient.providesGetLogin().getAccessToken()
apiLogin.enqueue(object : Callback<LoginResponse> {
override fun onResponse(call: Call<LoginResponse>, response: Response<LoginResponse>) {
if(response.isSuccessful){
if(response.body()?.code == 0){
Toast.makeText(this#LoginActivity, "Login Successful!", Toast.LENGTH_SHORT).show()
val intent = Intent(this#LoginActivity, List_usersActivity::class.java)
startActivity(intent)
} else {
Toast.makeText(this#LoginActivity, "Login Failed.", Toast.LENGTH_SHORT).show()
}
}
}
override fun onFailure(call: Call<LoginResponse>, t: Throwable) {
Toast.makeText(this#LoginActivity, "Login Failed.", Toast.LENGTH_SHORT).show()
}
})
}
}

first and foremost, please use camel case on java and kotlin. We have standards in java and kotlin on programming. And i can see that you are trying to do DI, but, thats not how you do it in Android.
Anyways, you could do this a couple of ways without even using a singleton but by saving it on a storage. Options are Shared Preferences, Local Storage and SQLite. But, if you insist on using a singleton. You can do it like this:
object MySingleton { // This is how you declare singletons in kotlin
lateinit var token: String;
}
EDIT
So, from your comment, it looked like you need to store the token. You could start by using sharedpreferences(database would be better) and store the token there. I assume you don't know how to so here is an example:
val sp = SharedPreferences("sp", 0);
sp.edit().putString("token", theTokenVariable); // not sure of this function
sp.edit().apply(); // you could use commit if you dont mind sharedpreferences to lag your screen(if it ever will)
Now how do you get the token from retrofit? The only way i could help you right now is that you could retrieve the response body from the response variable you receive from onResponse of the retrofit call. From there it is your problem mate. I don't know how your response is formatted, how it should be retrieved etc. A recommendation would be to format it as JSON.