With Android, Google set out to create a reliable, open-source mobile operating system. Since its release, Android has grown to become the most widely used mobile operating system in the world and to keep it intact, Android testing is needed with a suitable mobile app test automation framework. This is where Espresso comes into the act as it is a framework that helps you write UI tests for Android applications. You can use it to perform both synchronous and asynchronous tests.
An app under test's UI freezes when Espresso is running, which means your tests will be easier to write and maintain. In this guide, we will learn how to write UI tests using Espresso. We will explore the basics of writing Espresso tests and then move onto some more advanced techniques. On the way, we'll summarize what Espresso is good and not so good at doing. There is a lot we can learn from this framework and it's important to use it correctly. For example, some of the patterns and practices that work well with write unit tests can cause issues with tests that run on Android emulators or on real devices.
Introduction to Espresso
Espresso is a framework for Android apps that you can use to create tests of your UI. Espresso's main goal is to make UI testing fast and simple, so that you can easily test the correctness of your app's user interface regardless of its size.
- Espresso tests are written using the same language - Java or Kotlin - as the rest of your app. Although this means that writing an Espresso test requires more code than a feature spec, it also means that you are able to test all parts of your app's user interface.
- Using Espresso allows you to write tests with a clean, easy-to-use API. You can quickly build out tests for your various app components without getting bogged down in low level details.
- This means fewer typos and less maintenance, which leads to more robust apps with higher quality code. As an added bonus, Espresso not only makes your tests easier to read and maintain, it also automatically handles synchronization and cleanup of the Activity or Fragment under test.
The hard bugs you'll experience with normal Android instrumentation tests are also largely eliminated by Espresso. It helps automate interactions with user interfaces, letting you test particular events and parts of your app more effectively. This allows you to write code that is both more reliable and more concise, leading to high-quality applications.
Why should testers use Espresso?
Espresso makes it much easier to write and execute Android UI tests. It is tightly integrated with Android Studio, and as a result, it will allow you to quickly add UI tests to your existing Android codebase. However, apart from it, there are some benefits of using Espressor which makes it a suitable framework in the field of mobile app testing.
1. Easy and Quick Testing
The Espresso Android test automation framework is a perfect tool to test Android functions. It is robust, reliable, and has an important advantage: it offers the possibility of performing synchronized test cycles. Furthermore, it empowers the developer to test their application by performing asynchronous operations. With Espresso, they are already on the screen ready to be interacted with when the test is executed. When a test requires that you interact with an Element that is not currently possible, a failure is automatically registered.
2. Simple Documentation
Espresso is seen as the most powerful and growing Android instrumentation framework. It relies on a system of Action objects, rules, Idling Resources, and synchronization. Basically, all of these attributes work together to create a test code which can be applied multiple times with high consistency. Because its documentation is simple and the tests are not specific to any application and should be repeatable with each new application. Furthermore, it tracks what works and what doesn't with their ever-evolving codebase, regardless of their background or skill level.
3. Quick Feedbacks
Android Espresso is one of the many developer tools available to Android app developers. It has a byte code manipulation engine, which allows the developer to write tests using Java expressions and methods. This makes Espresso more powerful than other test automation frameworks, since it can test more natural user interactions, such as touch gestures. With Espresso, you can easily simulate user interactions like clicking buttons or entering text in text fields. Plus, this tool will give you faster feedback about your application with each development iteration.
Setting up Espresso for Mobile App Testing
Espresso is a library that facilitates writing Android UI tests. It provides a rich set of annotations and support classes to make writing an automated UI test for Android applications straightforward. Espresso can be complementary with other testing frameworks in the Android ecosystem like Robotium, Appium, etc. However, Espresso gives freedom to the users to understand and choose the way they want to perform the mobile app testing. But before it, we have to install and set it up for it.
For installing Expresso, the tester needs to make sure that he is having
- An emulator having Android 4.1 version or more than that.
- A device with Android SDK present in it.
- Android Studio with higher version than 2.0
After making sure that these requirements are met with the system that you are having, the process can be started.
For Windows
- The first step is to start the Android Emulator and then to connect it with the device on which you want to test.
- Then run the command Run gradlew.bat connectedAndroidTest.
For Mac/OS
- The first step is to start the Android Emulator and then to connect it with the device on which you want to test.
- Then run the command Run./gradlew connectedAndroidTest
Some time ago all testing was done in the same environment as, and similar to, the environment to be shipped. However, as software became more complex and test suites more difficult to maintain, it was difficult to secure a clean test environment, making it essential to develop automated tests.
Working of Espresso in Mobile App Testing
Espresso is more than a testing tool. It is designed for high-performance UI testing; hence, it uses different APIs than Instrumentation. This justifies why Espresso is a separate framework and will not be integrated into the larger test suite. InstrumentationTestBase, which launches activities by calling its public methods, simply does not scale because of the great number of tests required, especially when you need to examine a large number of elements in the same View (for example, buttons).
1. Finding Views
XML allows you to easily configure and change views. Espresso provides a number of different ViewMatcher classes which can be used for finding views. Android provides these view matchers and many other matchers for supporting complex view matching expressions in test code. Furthermore, for finding views, it is the most important component of Espresso which is useful for the testers.
2. Checking and Testing the views
There are several different assertions you can use to check the views. All of them are static methods on the ViewAssertion class, which is in the Android.test package. Apart from it, testing and checking whether the views have been enabled is an important part of the process which makes it easier for the testers to see where the problem lies and how they can improve in the future.
3. Performing actions on the views
Espresso allows you to locate views within your app, interact with them and check for expected results. One of Espresso's most powerful features is its ability to test for view interactions. This means you can write tests that check if a user can interact with your app in the way you expect them to. If you want to check that the button is clickable, or that a certain menu's items are visible to the user, then there's no better tool than Espresso.
4. Cleaning the tests after seeing the views
Espresso has many features that make it easy to write unit tests for your app. One of the most important is its ability to test the interactions between views and buttons, text, list items, etc. This allows you to verify if the UI of your app behaves as expected. However, once all these things are done, it is essential to clean the tests so that other tests can be performed and they don’t get any errors.
Automation Tests present in Espresso
Espresso was built with the idea in mind that testing user interactions is not an art, but a science. There are established patterns and best practices for it. This means you don't have to figure them out yourself or search online. Espresso supports these best practices and allows you to take advantage of them in your projects. Furthermore, the tests involved in Espresso have always been designed in order to make things easier for the testers. Currently, there are two types of tests that are performed by Espresso. These are:
1. UI Tests
UI testing is a feature that enables developers to write automated UI (User Interface) tests. Espresso uses the instrumentation framework in Android to execute tests. It is a great way to test your app's functionality: create a new UI test to check your activity's layout, verify the appearance of text and icons, and test the functionality of buttons and other user interface elements. Furthermore, these tests can be run on either a real device or in an emulator, so they are especially useful for testing the appearance and behavior of user interface elements under realistic conditions. Apart from it, UI tests are always carried out to make sure that the user’s aren't facing any problem while accessing the site. Besides this, you can verify that an image has the correct content, or test that text left in the soft keyboard is dismissed when pressing a button. Espresso tests are used to ensure that every piece of UI does what it's supposed to do before taking any further action.
2. Functional Tests
Functional tests are automated tests that verify the behavior of an application or user interface by simulating user input. Espresso is a framework included in Android Testing Support Library for writing functional UI tests for Android apps. These tests can be run during the development phase to ensure that UI changes do not break previously working application logic. tests are used to automate UI functional tests. One of the main reasons for using functional tests is to get fast feedback. You generally don't want to wait hours or even minutes for a test to complete, collect the logs and run through the steps to see if the app reacts correctly or not. This way you can run all your tasks at once and get the results faster. You can even run them periodically as part of your build process.
How to get started with Espresso using LambdaTest?
Espresso is a top-notch framework for test automation. It is therefore crucial to execute Espresso testing efficiently. Scaling up Android device labs can be costly and difficult. In order to solve this problem, a platform like LambdaTest is needed that allows users to test devices on the cloud without having to set up an in-house testing infrastructure. LambdaTest's online device farm allows developers and testers to test Espresso on real Android devices anytime, anywhere.
Wrapping Up
Espresso is used to test just the UI layer of your app. It will not work with any services that are accessed directly by an app's main process such as network connections, databases, or local storage. These types of components require a different approach. You can use Spock framework or Robotium for testing non-UI components like this. Espresso can also be integrated with other test automation frameworks such as Appium and UiAutomator.
Following this guide will help you develop Espresso tests that are fast, reliable, maintainable and readable. With these tips and best practices in your toolbelt, you're ready to take your Espresso testing skills to the next level. While Espresso is a good tool for Android app testing, it doesn't solve every need in your app's testability regime. The next step after mastering Espresso is to investigate other complementary tools and libraries for writing more robust and complete automated tests.
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