Android : Mock Response with Retrofit & OkHttp

AndroidRetrofitOkHttp.kt

class LoginInterceptor: Interceptor{
    override fun intercept(chain: Interceptor.Chain): Response {
        //If requested endpoint matched to targeted endpoint, we will return an mocked response.
        if (chain.request().url.toUri().toString().endsWith("fake-login")) {
            val responseString = "OUR_JSON_RESPONSE_FROM_ASSET_OR_OTHER_SOURCE"
            return chain.proceed(chain.request())
                .newBuilder()
                .code(200)
                .protocol(Protocol.HTTP_2)
                .message(responseString)
                .body(
                    responseString
                        .toByteArray()
                        .toResponseBody(
                            "application/json".toMediaTypeOrNull()
                        )
                )
                .addHeader("content-type", "application/json")
                .build()
        } else {
            //Skip the interception.
            return chain.proceed(chain.request())
        }
    }
}

object RetrofitProvider {
    //Return a lazy instance of OkHttp client
    private val myHttpClient: OkHttpClient by lazy {
        val ins = OkHttpClient().newBuilder()
            .connectTimeout(1, TimeUnit.MINUTES)
            .readTimeout(1, TimeUnit.MINUTES)
            .writeTimeout(1, TimeUnit.MINUTES)
            .retryOnConnectionFailure(true)
        //Adding our LoginInterceptor only on Debug mode only
        if (BuildConfig.DEBUG){
            ins.addInterceptor(LoginInterceptor())
        }
        ins.build()
    }

    //Public access point for Mock API Service
    fun getMockAPI(): MockAPIEndpoint = retrofitInstance.create(MockAPIEndpoint::class.java)

    //Return a lazy Retrofit instance
    private val retrofitInstance: Retrofit by lazy {
        Retrofit.Builder()
            .baseUrl("https://rommansabbir/api/v2/")
            .client(myHttpClient)
            .build()
    }
}