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Android Arsenal Circle CI

REST API mocking made easy.

RESTMock is a library working on top of Square's okhttp/MockWebServer. It allows you to specify Hamcrest matchers to match HTTP requests and specify what response to return. It is as easy as:

            .thenReturnFile(200, "users/andrzejchm.json");


Table of contents


Here are the basic rules to set up RESTMock for Android

Step 1: Repository

Add it in your root build.gradle at the end of repositories:

allprojects {
	repositories {
		maven { url "" }

Step 2: Dependencies

Add the dependency

dependencies {
	androidTestImplementation 'com.github.andrzejchm.RESTMock:android:${LATEST_VERSION}' // see "Releases" tab for latest version

Step 3: Start the server

It's good to start server before the tested application starts, there are few methods:

a) RESTMockTestRunner

To make it simple you can just use the predefined RESTMockTestRunner in your UI tests. It extends AndroidJUnitRunner:

defaultConfig {
    	testInstrumentationRunner ''
b) RESTMockServerStarter

If you have your custom test runner and you can't extend RESTMockTestRunner, you can always just call the RESTMockServerStarter. Actually RESTMockTestRunner is doing exactly the same thing:

public class MyAppTestRunner extends AndroidJUnitRunner {
	public void onCreate(Bundle arguments) {
		RESTMockServerStarter.startSync(new AndroidAssetsFileParser(getContext()),new AndroidLogger());

Step 4: Specify Mocks

a) Files

By default, the RESTMockTestRunner uses AndroidAssetsFileParser as a mocks file parser, which reads the files from the assets folder. To make them visible for the RESTMock you have to put them in the correct folder in your project, for example:


This can be accessed like this:

            .thenReturnFile(200, "users/defunkt.json");
b) Strings

If the response You wish to return is simple, you can just specify a string:

            .thenReturnString(200, "{}");
c) MockResponse

If you wish to have a greater control over the response, you can pass the MockResponse

RESTMockServer.whenGET(pathContains("users/defunkt")).thenReturn(new MockResponse().setBody("").setResponseCode(401).addHeader("Header","Value"));
c) MockAnswer

You can always build dynamic MockResponses by using the RecordedRequest object

RESTMockServer.whenGET(pathContains("users/defunkt")).thenAnswer(new MockAnswer() {

            public MockResponse answer(RecordedRequest request) {
                    return new MockResponse()

Step 5: Request Matchers

You can either use some of the predefined matchers from RequestMatchers util class, or create your own. remember to extend from RequestMatcher

Step 6: Specify API Endpoint

The most important step, in order for your app to communicate with the testServer, you have to specify it as an endpoint for all your API calls. For that, you can use the RESTMockServer.getUrl(). If you use Retrofit, it is as easy as:

RestAdapter adapter = new RestAdapter.Builder()

take a look at #68 for better reference


By default, RESTMockServer will serve responses using Http. In order to use HTTPS, during initialization you have to pass RESTMockOptions object with useHttps set to true:

RESTMockServerStarter.startSync(new AndroidAssetsFileParser(getContext()),new AndroidLogger(), new RESTMockOptions.Builder().useHttps(true).build());

there is a possibility to set up your own SSLSocketFactory and TrustManager, if you do not specify those, then default ones will be created for you. You can easly retrieve them with RESTMockServer.getSSLSocketFactory() and RESTMockServer.getTrustManager() to be able to build your client that will accept the default certificate:

new OkHttpClient.Builder().sslSocketFactory(RESTMockServer.getSSLSocketFactory(), RESTMockServer.getTrustManager()).build();

A sample how to use https with RESTMock in android tests can be found in androidsample gradle module within this repository.

Response chains

You can chain different responses for a single request matcher, all the thenReturn*() methods accept varags parameter with response, or you can call those methods multiple times on a single matcher, examples:

                .thenReturnString("a single call")


                .thenReturnString("a single call", "answer no 2", "answer no 3");

Response body delays

Delaying responses is accomplished with the delayBody(TimeUnit timeUnit, long delay) and delayHeaders(TimeUnit timeUnit, long delay) method. Delays can be specified in chain, just like chaining responses:

                .thenReturnString("a single call")
                .delayBody(TimeUnit.SECONDS, 5)
                .delayBody(TimeUnit.SECONDS, 10)
                .delayBody(TimeUnit.SECONDS, 15);


                .thenReturnString("a single call")
                .delayBody(TimeUnit.SECONDS, 5, 10, 15);

Which will result in 1st response body being delayed by 5 seconds, 2nd response by 10 seconds and 3rd, 4th, 5th... by 15 seconds.

Response header delays

Mechanics of the responseHeader(...) method are the same as those in responseBody(...). The only difference is that response headers are being delivered with a delay. This comes handy if your app is acting on response headers, which would've been delivered immediately if you used the delayBody(...) method.

Interleaving delays with responses

Check out this example:

                .thenReturnString("1st call")
                .delay(TimeUnit.SECONDS, 5)
                .thenReturnString("2nd call")
                .delay(TimeUnit.SECONDS, 10)
                .delay(TimeUnit.SECONDS, 15)
                .thenReturnString("3rd call")
                .delay(TimeUnit.SECONDS, 20, 30, 40)

this will result in 1st call being delayed by 5 seconds, 2nd call delayed by 10 seconds, 3rd call delayed by 15 seconds, another one by 20 seconds, and another by 30 seconds, and then every consecutive response with 40 seconds delay

Request verification

It is possible to verify which requests were called and how many times thanks to RequestsVerifier. All you have to do is call one of these:

//cheks if the GET request was invoked exactly 2 times

//cheks if the GET request was invoked at least 3 times

//cheks if the GET request was invoked exactly 1 time

//cheks if the GET request was never invoked

Additionaly, you can manualy inspect requests received by RESTMockServer. All you have to do is to obtain them trough:

//gets 5 most recent requests received. (ordered from oldest to newest)

//gets 5 oldest requests received. (ordered from oldest to newest)

//gets all GET requests.  (ordered from oldest to newest)


RESTMock supports logging events. You just have to provide the RESTMock with the implementation of RESTMockLogger. For Android there is an AndroidLogger implemented already. All you have to do is use the RESTMockTestRunner or call

RESTMockServerStarter.startSync(new AndroidAssetsFileParser(getContext()),new AndroidLogger(), new RESTMockOptions());



Android Sample Project

You can check out the sample Android app with tests here


If you think the library is awesome and want to buy me a beer, you can do so by sending some...

  • Ethereum ETH here: 0xf7354a0F7B34A380f6d68a2661bE465C10D6AEd7
  • Bitcoin BTC here: 12bU3BMibFqbBBymaftXTDnoHojFymD7a6
  • NEO NEO or GAS here: AX1ovzRN2N28WJrtehjYXjwtHSvcqva6Ri


Copyright (C) 2016

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
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Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
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