UI Testing in Android


Testing in android is something that most people simply don’t do. When I first started with developing android apps, I followed the same dev cycle :

  • Develop a feature
  • deploy to a device
  • manual testing for bugs and errors
  • fix these issues due to wrong implementation
  • then again deploy and manually test and so on……

Trust me it’s a tedious process and no one actually can test for the corner cases that may arise. You may be able to cover like 85% of the cases for each feature but when there are a ton of features you’ll collectively cover much less than 85% as well. So, We should definitely write tests for android. I’ll start with Espresso testing first.

Quote from the Android developer website:


“Testing user interactions within a single app helps to ensure that users do not encounter unexpected results or have a poor experience when interacting with your app. You should get into the habit of creating user interface (UI) tests if you need to verify that the UI of your app is functioning correctly.

The Espresso testing framework, provided by the Android Testing Support Library, provides APIs for writing UI tests to simulate user interactions within a single target app. Espresso tests can run on devices running Android 2.2 (API level 8) and higher. A key benefit of using Espresso is that it provides automatic synchronization of test actions with the UI of the app you are testing. Espresso detects when the main thread is idle, so it is able to run your test commands at the appropriate time, improving the reliability of your tests. This capability also relieves you from having to adding any timing workarounds, such as a sleep period, in your test code.

The Espresso testing framework is an instrumentation-based API and works with theAndroidJUnitRunner test runner.”


Getting started

We first need to setup espresso in android studio. That can be done by adding this to the app level build.gradle

dependencies {
    ...
    androidTestCompile 'com.android.support.test.espresso:espresso-core:2.2.1'
}

After adding this dependency and setting up testing on android, now we can move on to write some tests. We start by adding a new class in androidTest where we will actually write the tests. There are 3 parts to writing an espresso test :

  1. ViewMatchers: Find a view to act/assert upon something
  2. ViewActions: something to perform an action(click, type etc.)
  3. ViewAssertion: something to verify what you expect

Components

  1. For writing tests in espresso we just have to use these three parts to see if the ui is working as it should.

    Let’s say we want to type some text in an edittext and see if the text we have typed is as we expect it to be.

    To start, we’ll see how we use viewMatchers. We need to find a view in ViewMatchers. For that, we will do something like this

    withId(R.id.edittext_id)

    Now we perform a click on this eddittext

    perform(typeText("Hello"))

    Now we join the two by wrapping in onView()

    onView(withId(R.id.edittext_id)).perform(typetext("Hello"))

    This will just type “Hello” in the edittext with the id eddittext_id, now we need to check if this is what was actually expected, for that we will have to further a viewAssertion on this like this :

    onView(withText("Hello")).check(matches(isDisplayed()));

    This is a cheatsheet that shows various methods that can be used in espresso.

    So this is how we can perform basic ui tests using espresso. Mainly people face the issue of deciding on the views that we have to perform this action on. Just think of the 3 components that we have previously talked about (View matching, View action and View assertions), if you think a view can have all three of these, then you can write a test for it. Go ahead and try it for yourself. Cheers!


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