Introduction to Automated Android Testing – Part 6

In the previous 5 blog posts, we covered different aspects of building an Android app from scratch. We focused on including tests in the process. Here are the links to the previous posts:

  • Post #1 – Why should we write tests?
  • Post #2 – Set up your app for testing
  • Post #3 – Creating API calls
  • Post #4 – Creating repositories
  • Post #5 – Following the MVP pattern

In this last post of the series, we will cover creating Espresso tests for the View we created in part 5. The Github repo for this post can be found here.

Testing that a view contains the exact information expected can be tricky if the data is dynamic. This data can change at any time and our tests should not fail because of it. In order for the tests to be reliable and repeatable, we should not call any production APIs.

Mocking out the responses of the API calls will enable us to write tests that depend on the mocked data. There are a couple of ways in which we can mock out our API calls:

  • Option 1 – Use WireMock and run a standalone server which serves up the same static JSON for specific network calls.
  • Option 2 – Use OkHttp’s MockWebServer which runs a webserver on your device and serves up any response you request.
  • Option 3 – Create a custom implementation of the Retrofit REST interface that returns dummy objects.

Obviously, the choice is entirely up to you as to how you would want to go about writing UI tests. In my case, WireMock is extra effort as I would need to ensure I have a standalone server running with a static IP address.

MockWebServer is a lot easier to use than WireMock as you don’t have to set up a standalone web server (The server runs on the device). MockWebServer is also flexible because you can give it different scenarios. Useful features like specifying the failure rate of a certain call or simulating a slow network are possible using MockWebServer. (Read more here).

I am going to use option 3 for the purpose of testing that the UI matches the mock response data. If I wanted to add tests for slow network conditions (or some kind of non-functional test), I would choose option 2. If you are unable to use OkHttp,  I would choose option 1 as Wiremock works with any HTTP client.

Mocking out data using Gradle flavors

By making use of Gradle flavors, we can easily mock out of API responses.  If you read post #2 on Gradle flavors, you should already have a “mock” and a “production” flavor set up.

  1. Make sure you are switched to the mockDebug flavor. Select mockDebug variant
  2. Create a mock folder in the src directory. Then create a package within the mock folder, that mimics the main package name. Make a class called MockGithubUserRestServiceImpl. Your resulting file structure should look like this: Folder structure for mock testing
  3. Create a prod directory. Move the Injection class defined previously into this folder. We will be creating another Injection class in the mock folder. This class will inject the mocked out Github service instead of the production API. Move Injection to prod and create one in mock folderIn the Injection class that is located in the mock folder, we simply return the MockGithubUserServiceImpl that we created. In the prod folder, we return the actual Retrofit Github service. [adwords_square]
    Mock Injection class:

    Prod Injection class:
  4. The data returned from the mock service is dependant on your specific requirements. Below is my implementation of the MockGithubUserRestServiceImpl:

    In this case, I am just returning some dummy data. Let’s run the mock version of the app and we should get the same results no matter what you search.

    Android Test app with mock data

    Cool. Now we have a working dummy app! We can now write Espresso UI tests. [adwords_square]

Basics of Writing an Espresso Test

When writing an Espresso test, the following formula is used for performing functions within your UI:

  • ViewMatchers – Used to find a view in an activity. There are a bunch of different kinds of matchers. For example: withId(, withText("Search"), withTag("custom_tag") .
  • ViewActions – Used to interact with a view. For example: click(), doubleClick(), swipeUp(), typeText().
  • ViewAssertations – Used to make assertions that certain views possess specific properties. For example:   doesNotExist(), isAbove(), isBelow().

There is a great cheat sheet for the different Espresso methods that can be found in pdf form here: android-espresso-testing.pdf. It is worth mentioning that ordinary hamcrest matchers can be used when writing Espresso tests. Methods such as not(), allOf()  and anyOf() are valid.

Writing Espresso UI Tests

If you can recall, in post #2 we covered what dependencies will need to be added in order to write espresso tests. Now we will cover writing an Espresso test.

  1. Create a folder androidTestMock. The tests in this folder will only run on the mock variant and not on the production variant. Then make a directory that matches the main package name. In that directory, add a new class called  UserSearchActivityTest. Your project should then look like this:androidTestMock folder
  2. We will start by writing a basic test that ensures that when the activity is started, the text “Start typing to search” is displayed:

    The @Rule  ActivityTestRule specifies which activity this test will run with. In this case this test will run with UserSearchActivity. This will automatically start up the UserSearchActivity. Passing extra parameters will indicate if you want the activity to auto start or not.

    The test searchActivity_onLaunch_HintTextDisplayed() is quite simple. It searches in the view for the text and asserts that the text is visible on the UI.

  3. The next test is slightly more complicated:

    After typing into the SearchView and pressing enter, we assert that the dummy results are displayed on the UI.

  4. We have now written tests for the positive scenarios, we should add a test for the negative case too. We will need to adjust the MockGithubUserRestServiceImpl in order to allow it to return custom error observables if required.

    In the code above, a method was created in order to set a dummy observable for the search results. That observable will be returned if it is not null when searchGithubUsers() is called.

  5. Now we can create a test that checks if the error is displayed on the UI.

    In this test, we first ensure that the service will return an exception. Then we assert that the error message is displayed on the UI.

  6. Let’s run the tests:


They all pass!

Code Coverage in Android

In order to know how effective your tests are, it is great to get code coverage metrics.

  1. To enable code coverage on your UI tests, add testCoverageEnabled = true  to your build.gradle:
  2. Run the task createMockDebugCoverageReport. You will then find the HTML report located here: app/build/reports/coverage/mock/debug/index.html.

Code Coverage Report in Android

Yay – we have 82% coverage just with the mock UI test. Taking into consideration the coverage reports we saw in post #4 and this post, it gives us a good indication of the test coverage of our entire app. Now we can iteratively go back and try cover more areas of our code.

PS – Code coverage currently doesn’t work with the Jack compiler. I switched to use Retrolambda in order to get the code coverage report to work. If you are interested in learning more, check out this branch.


We have finished writing our feature. Whew! 6 blog posts later. There is obviously a lot more testing that can be completed in this app. Non-functional tests such as testing how your app behaves on devices with low memory or with poor network connectivity can also be added.
That concludes the series on an “Introduction to Automated Android Testing”. I hope you enjoyed reading this series. If you enjoyed it, be sure to subscribe to the blog to receive future updates and share the post with your friends.

Further Reading

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Introduction to Automated Android Testing – Part 5

In this series of blog posts, we are working through a sample app called Github User Search. Parts 1 – 4 covered why we should test, getting set up with testing, creating API calls and creating a presenter. Take a look at the previous posts as part 5 is a continuation of the series.

In part 5, we will take a look at interacting with the Presenter  created in part 4 and we will create the UI to display the list of search results.

Creating the UI

For the User Interface we want a simple list that displays the avatar, name and other user information in the list.

In part 4, we defined a View contract which the Activity should implement. This is where the Android specific code will be located (things such as visibility changes or any UI changes will be located here). To refresh your memory, this is the View contract we created in this last post:

Let’s implement the View! [adwords_square]

  1. Create a class called  UserSearchActivity. This class will implement the UserSearchContract.View contract and extend AppCompatActivity. Define a variable called userSearchPresenter of type UserSearchContract.Presenter. This is the object that we will interact with in order to perform our network calls.

    In onCreate(), create the presenter object. Provide it with the User repo defined in the Injection class. Pass the io() scheduler and the AndroidSchedulers.mainThread() scheduler so that the RxJava subscriptions know which threads they should perform their work on.

    On the next line, you can see I call userSearchPresenter.attachView(this) . This attaches the view to the presenter, so that the presenter can notify the view of any changes. Because the presenter isn’t aware of the activity’s lifecycle, in onDestroy() we need to inform the presenter that the view is no longer in existence, so we should then call userSearchPresenter.detachView(). This will unregister any RxJava subscriptions and prevent memory leaks from occurring.

  2. Create activity_user_search.xml in the layout folder. This will contain a RecyclerView, a ProgressBar, an error TextView and a Toolbar. I am using ConstraintLayout to design my screen, so I won’t go into too much detail as it is mostly drag and drop. (If you want to read more about ConstraintLayout check out my blog post about it here)UserSearchActivity

  3. We also need to add a SearchView to the toolbar so we have somewhere to type. Add a menu_user_search.xml file to the menu resource folder. Inside it, you will need to add a SearchView:

  4. We need to create a layout that will be used for each item in the RecyclerView. Create a file named list_item_user.xml in the layout folder. I used ConstraintLayout with one ImageView for the avatar and two TextViews.List_item_user_designmode

  5. Now that we have all the layouts we need, let’s tie the XML to the Activity. First, in onCreate() we will get references to the views we need.

  6. We need to hook the SearchView up into our activity to make it trigger the presenters search() method. In the onCreateOptionsMenu(), add the following code:

    This will inflate the correct menu, find the search view and set a query text listener. In this case, only when someone presses submit on the keyboard, we will respond by calling the search presenter with the query. We could do it in onQueryTextChange too but due to rate limiting on the Github API I will stick to onQueryTextSubmit. By default, the item will be expanded.[adwords_square]

  7. Next, we will implement the callbacks that the presenter will call when the items are finished loading.

    We are basically just toggling visibility of views here and setting the usersAdapter  to the new items that the service returned.

  8. For completeness, here is the UserSearchAdapter class which is used for the RecyclerView on the activity:


    Injection class

  9. Now if you run the app, you should be able to search for a username on Github and see results.github_user_search

Yay! We have a working app. Code for this post can be found here. In the next part, we will look at writing UI tests for the app. Make sure you subscribe so you don’t miss a post!

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Introduction to Automated Android Testing – Part 4

In this blog post series, we are working through an example Android app called Github User Search. In the previous blog posts, we took a look at setting up your app for testing, creating API calls and writing the first basic test for the API transformations. Read part 1, part 2 and part 3 first.

This post will look at creating a presenter which communicates with the repository and conveys information to the view. This will also include writing unit tests for the presenter. The sample github repo this blog post will be working from can be found here.

Creating the Presenter

  1. In order to get started, create base interfaces called MvpView and MvpPresenter. All MVP functionality will extend these two interfaces.

  2. Create a BasePresenter. This will provide functionality to check whether a view is attached to the presenter and a way to manage RxJava subscriptions.

    As you can see above, there is a CompositeSubscription defined in the presenter. This object will hold a group of RxJava subscriptions. The detachView() method calls  compositeSubscription.clear() which will unsubscribe from all subscriptions, prevent memory leaks and view crashes (code will not run when the view is destroyed as it is unsubscribed). When a subscription is created in a presenter that subclasses this object, we will call addSubscription()
  3. Create the contracts between the view and the presenter in a class called UserSearchContract. Within this class, create two interfaces one for the view and one for the presenter.

    In the view, there are 4 methods, showSearchResults()showLoading(), hideLoading(), showError(). In the presenter, there is a method called search().

    A presenter does not care about how a view shows the results, nor how it shows an error. Similarly, a view doesn’t care how a presenter searches as long as it uses those callbacks to notify, the implementation doesn’t matter. [adwords_square]

    Separating the logic between the view and presenter is simple. Think about reusing the presenter for another type of UI and that will make you realise where the code should live. For instance, if you had to use Java Swing, your presenter can remain the same in that case, only your view implementation would differ. This helps you to place logic by simply asking yourself the question: Would the logic in the presenter make sense if I had a different type of UI?

  4. Now that the contracts between the view and the presenter are defined. Create/navigate to UserSearchPresenter. This is where a subscription to the UserRepository will be created, which will call the Github API.

    Here the presenter extends BasePresenter  and implements the UserSearchContract.Presenter contract defined in step 3. This class will implement the search() method.

    Using constructor injection allows easy mocking of the UserRepository when trying to do unit testing. The schedulers are also injected into the constructor, as the unit tests will always use Schedulers.immediate() but in the view we will use different threads.

  5.  Now for the implementation of search() :

    First off, run checkViewAttached() this will throw an exception if the view is not attached when the method starts running. Then tell the view that it should start loading by calling  showLoading(). Create a subscription to  userRepository.searchUsers(). Set subscribeOn() to the ioScheduler variable as we want these network calls to happen on the IO Thread. Set observeOn()  the mainScheduler  as we want the result of this subscription to be observed on the main thread. Then add the subscription to our composite subscription by calling addSubscription.[adwords_square]

In the onNext() method, handle the result by calling hideLoading() and showSearchResults() with the list of users returned by the API. In onError(), stop the loading and call showError() with the exception’s message.

Here is the full code for UserSearchPresenter :

Writing Unit Tests for the UserSearchPresenter

Now that the presenter is defined, let’s create some unit tests for it.

  1. Select the UserSearchPresenter class name. Press “ALT + Enter” and select “Create Test”. Select the “app/src/test/java” folder as this is a unit test that requires no Android dependencies.  The resulting location of the test is the following: app/src/test/java/za/co/riggaroo/gus/presentation
  2. In the UserSearchPresenterTest, create the setup method and define the variables needed for testing.

    By creating a mock instance of  UserRepository and the UserSearchContract.View we will ensure that we are only testing the UserSearchPresenter. In the setUp() method, we call MockitoAnnotations.initMocks() . Then create the search presenter with the mocked objects and immediate schedulers. Call attachView() with the mock view object as the presenter works only once a view is attached.
  3. The first test will test that a valid search term has the correct callbacks:

    This test asserts that: Given the user repository returns a set of users, when calling  search() on the presenter, then the view methods showLoading() and showSearchResults() are called. This test also asserts that the showError() method is never called.
  4. The next test is one that tests the negative scenario if the UserRepository throws an error:

    This test is testing the following: Given the userRepository  returns an exception, when calling search()  then showError() should be called.
  5. The last test we will add will assert that if the view is not attached, an exception will be thrown.
  6. Let’s run the tests and see how much test coverage we have. Right click on the test name and click “Run tests with coverage”Unit Test Coverage from the Presenter Test

We have 100% Coverage of the UserSearchPresenter! Yay!

The next blog post will cover creating the view and writing tests for the view. Make sure you subscribe so you don’t miss the next post in this series!

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This post series was based on a couple of implementations of MVP that can be found around the web. For reference, these are some of the articles used to get to this solution:

Introduction to Automated Android Testing – Part 1

I’ve seen a lot of people confused and unsure about how to do tests in Android. In the past, it was very difficult to test Android apps and there wasn’t much direction. In this series, I am going to try make testing a bit easier for you. This first post is just to get you started with testing, the next few will go more in depth into testing in Android. Let’s get started!

Android Testing

Why should I test anyway?

You probably don’t really need convincing, since you are already reading this blog post. Here are some reasons why I like to write tests:

  • Testing forces you to think in a different way and implicitly makes your code cleaner in the process.
  • You feel more confident about your code if it has tests.
  • Shiny green status bars and cool reports detailing how much of your code is covered are both consequences of writing tests.
  • Regression testing is made a lot easier, as automated tests would pick up the bugs first.

Regression testing is the biggest benefit for me. If you refactor and your tests still pass, you will be confident that you haven’t broken anything. The problem with testing is that you might not see the benefit of testing immediately, as the true value will only surface a couple of months later when you need to refactor.

What types of testing are there in Android?

Unit Testing

A unit test generally exercises the functionality of the smallest possible unit of code (which could be a method, class, or component) in a repeatable way.

Tools that are used to do this testing:

  • JUnit – normal test assertions.
  • Mockito – mocking out other classes that are not under test.
  • PowerMock – mocking out static classes such as Android Environment  class etc.

UI Testing – Instrumentation Tests

A UI Test or Instrumentation Test mocks typical user interactions with your app. Clicking on buttons, typing in text are some of the things UI Tests can complete.

Tools that are used to do this testing:

  • Espresso –  Used for testing within your app, selecting items, making sure something is visible. 
  • UIAutomator – Used for testing interaction between different apps.

There are other tools that are available for this kind of testing such as RobotiumAppiumCalabashRobolectric

What do I need to get started with Automated Testing?

In order for you to get started with automated testing in your app, you should follow some kind of architectural pattern that will help you test and structure your app in a clean, testable way. One such pattern that easily enables testing is Model View Presenter (MVP) for Views and Repository Pattern for Networking and Database Access.

Of course, this is not the only option for you as an Android Developer, it is one of the many that you can explore in order to get test coverage and a clean architecture.

I have found it very difficult to implement tests without having a defined structure, often my tests were useless and I didn’t know what to test, it was also very difficult to get code coverage on large apps. My UI tests were also not very reliable as they were testing against production servers. Hopefully we can address these issues in this blog series.

Structure your App in a Testable Way

Here is a diagram depicting the structure I will use as a guideline for the rest of the blog post series:

Basic Structure Of Android App that will allow for Automated Testing

  • Views  – Activities and Fragments. This is where we set text and make UI changes. I typically like to keep the Android specific code in this section and try not to pass a context further than the view, obviously this is not always easy but it is good guidance to try follow. Views should only talk to presenters.
  • Presenters – This is where business logic to decide what should be displayed on the views is going to go.  Presenters talk to the repositories to get information out, and convey information to the Views. Try avoid putting Android specific code in your presenter if you can avoid it as it will make unit testing more difficult.
  • Repositories – Decide where to get data from, should they come from local persisted data? Or should the data come from the network? Repositories talk to presenters.
  • Models – Typically POJOs, these are models that are used by the Presenter and the View to convey information to the View from the Presenter.

Unit tests will test the Presenters and the Repositories. UI Tests will test the View all the way down to the repositories.

There are many great articles describing MVP and other architecture options – this blog post is not going to go into those details. Read more about different Android architectures here, here and here.

Where are Automated Tests placed in my Android app?

In your Android app folder structure, there are two folders that will house the tests:  test  and androidTest

Automated testing in Android

androidTest  – Android Instrumentation Tests are located here. The tests in this folder need to run on an Android Emulator or physical device.

test/ – Unit tests are placed in this folder. Unit Tests run on the JVM on your local machine and do not run on an Android device or emulator. This means they do not have access to Android classes (such as the Context  class).

Now that we are aware of the different kinds of tests and where to place in them in our apps. The next post we will go deeper into how to structure your code in order to allow for better unit testing. Check out Part 2 here!

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Automated Testing of SQLite Database Upgrades – Android

As a follow up to my previous post [How to use onUpgrade() correctly in Android], I decided that I should probably add some tests to avoid database upgrade failures in the future. Manually testing database upgrades in Android can be quite a pain and you are bound to miss something, especially if you have had loads of versions of your application released. [adwords_square]

How to test SQLite database upgrades manually

  1. Install the old APK.
  2. Test your app to get the database filled with data that you need to test the upgrade on.
  3. Install the new version of your app over the old version. Test that nothing is broken and that the database upgrades as expected.
  4. Repeat. This process would need to be repeated for every database version that you have released. (In my case its something like 30 versions of the database 😑)

Testing 30+ different versions of your application is a tedious process and you are most likely to miss something in one of the tests.

How to test SQLite Database Upgrades automatically:

I decided to try add at least a basic test to the Github Project that demos Android Database Upgrades .

The test is simple: Instead of uninstalling one version of the app and installing the new one on top of it, it copies a version of the database from the /androidTest/assets/ folder and then performs an upgrade on that version to the latest version of your application.

If there is any issue with the upgrade, typically a SQLException will be thrown and the test will fail.[adwords_square]

The following class is the test for upgrading your SQLite database.

The  testDatabaseUpgrades()  method requires that every time you release a new database version, you archive it in your androidTest/asset/ folder and name it database_v1.db etc.

SQLite Automated Database Upgrades in Android

It is advisable to do it with a database filled with data that needs to be migrated and not an empty one. You can obviously extend this kind of testing to do specific upgrade tests if there is a bigger complexity to your upgrade.

You can checkout the Github Project here for the full source code.

How do you test SQLite database upgrades? Leave a comment below!