How to fake a network response with Retrofit2?

gistfile1.txt

//  step 1 - make a fake response interceptor
class FakeResponseInterceptor : Interceptor {

        @Throws(IOException::class)
        override fun intercept(chain: Interceptor.Chain): Response? {
            val responseString = "{\n" +
                    "\t\"name\": \"audhil\",\n" +
                    "\t\"occupation\": \"android developer\"\n" +
                    "}"
            var response: Response? = null
            response = Response.Builder()
                    .code(200)
                    .message(responseString)
                    .request(chain.request())
                    .protocol(Protocol.HTTP_1_0)
                    .body(ResponseBody.create(MediaType.parse("application/json"), responseString.toByteArray()))
//                        .addHeader("content-type", "application/json")
                    .build()
            return response
        }
    }
    
//  step 2 - make a OkHttpClient
private fun getHttpClientWithInterceptors(): OkHttpClient {
  val httpClient = OkHttpClient.Builder()
  httpClient.addInterceptor(HttpLoggingInterceptor().setLevel(HttpLoggingInterceptor.Level.BODY))
  httpClient.interceptors().add(FakeResponseInterceptor())
  return httpClient.build()
}

//  step 3 - add OkHttpClient in Retrofit2
private val retrofit = Retrofit.Builder()
                .baseUrl(".....")
                .addConverterFactory(GsonConverterFactory.create(GsonBuilder().create()))
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(getHttpClientWithInterceptors())
                .build()
var service = retrofit.create(APIService::class.java)