The War of the Test Frameworks: XCTest vs Espresso vs Appium

Introduction

We know the running war of the test frameworks: XCTest vs Espresso vs Appium. When deciding to start your journey towards mobile test automation, it’s important to have all of the information in front of you before choosing your automation tooling. If you (like many other teams out there) are currently trying to decide between Appium, Espresso, and XCTest / XCUITest, it’s very helpful to weigh the pros and cons of each approach. To try and make this easier, we have done the hard work for you and compiled information around what each solution is and what the pros and cons are.

Looking at the market, the predominant tool is still Appium, but native frameworks like Espresso (for Android) and XCTest/XCUITest (for iOS) are beginning to gain ground for a variety of reasons.

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XCUITest/XCTest

What Is XCTest and XCUITest?

`XCTest` and `XCUI Test` are both part of the XCTest framework provided by Apple for unit and UI testing of iOS and macOS applications. However, they serve different purposes within the testing ecosystem. Understanding the distinction between them is crucial for developers and testers aiming to implement comprehensive testing strategies for their apps.

XCTest

XCTest is primarily used for unit testing. It allows developers to test the smallest parts of an application, known as units, in isolation from the rest of the app. This includes testing individual functions and methods to ensure they perform as expected under various conditions. These various conditions include happy expected paths, as well as, handling edge cases and not-so-happy paths to ensure all logic is accounted for at the unit, foundational level.

Scope: The scope of XCTest is limited to testing the internal logic of the app. It doesn’t interact with the UI elements but focuses on the backend processes, algorithms, and app functionalities.

Use Cases: XCTest is ideal for early development stages when the focus is on validating the core logic and functionality of the app. It helps in identifying and fixing bugs at the code level before integrating the components into a larger system.

Execution: Tests written using XCTest can be run directly within the Xcode IDE. They are fast and efficient, making them suitable for frequent execution during the development process.

XCUITest

XCUITest is a native framework for UI testing on iOS mobile devices. Since XCUITest is baked right into Xcode IDE, it provides the fastest possible execution for iOS devices. 

Scope: The scope of XCUITest is broader than XCTest, as it encompasses the entire user interface. It simulates real user interactions by automating taps, swipes, and other gestures to navigate through the app’s UI.

Use Cases: XCUITest is used later in the development cycle, once the UI is developed and stable. It’s particularly useful for regression testing in end-to-end testing, ensuring that new code changes do not break UI elements and existing functionalities.

Execution: Like XCTest, XCUITests are also executed within the Xcode IDE. However, as one is testing smaller units and the other testing larger, UI elements and interactions, XCUITest tends to be slower than unit tests because they involve launching the app and navigating with the UI.

Pros

• XCTest provides a comprehensive testing framework that supports both unit testing (with XCTest itself) and UI testing (with XCUITest). This dual capability allows developers to cover a wide range of tests, from testing the smallest units of code to comprehensive UI tests.
• XCTest (including XCUITest) is fully integrated into Apple’s Xcode IDE, making it easily accessible for iOS developers and testers. This integration streamlines the testing process, from writing and running tests to analyzing results, all within a familiar environment.
• XCTest is fast. As of now, it is your fastest solution for unit testing iOS mobile applications.
• XCUITest is a great “anti-flake” option, since it helps develop UI tests that reflect the user interface by working directly at the object level. In doing so, tests have the ability to verify UI elements and their properties and navigate through the element hierarchy of your application. This helps create intuitive tests that are easy to maintain and reduces flakiness tremendously.
• XCUITest also provides XCUITest Recorder that records navigation through the user interface and helps users create scripts to quickly build test suites that can be run across actual devices or emulators/simulators.
• While traditionally more difficult to integrate into CI/CD pipelines than its Android counterpart, Espresso, XCUITest has made way headway into becoming easier to integrate into your CI processes.

Cons

• While XCTest excels in unit testing speed, UI testing with XCUITest can be slower, especially when running comprehensive UI test suites. This can impact the overall efficiency of the testing process. However, comparing to the other UI testing frameworks, XCUITest is the fastest UI automation for iOS.
• XCUITest is a great “anti-flake” option when testing on emulators and/or running unit tests, but this benefit does start to dwindle when testing on real devices.
• XCUITest is limited in its support for a variety of languages. As of now, XCUITest is limited to Objective C and Swift.
• XCTest / XCUITest is only for iOS and cannot help the team that needs to test on both iOS and Android devices.
• Developers new to XCUITest may face a learning curve, especially when it comes to understanding the UI testing APIs and dealing with dynamic UI elements or complex user interactions.

In summary, while both XCTest and XCUITest are crucial components of the XCTest framework, they cater to different testing needs. XCTest focuses on the internal logic and functionalities of the app, making it suitable for unit testing. In contrast, XCUITest deals with the app’s user interface, automating interactions to ensure a seamless user experience. Together, they provide a comprehensive testing suite that helps developers and testers ensure the quality and reliability of iOS and macOS applications.

Espresso

What is Espresso?

Like XCTest, Espresso is a native framework for UI testing. However, instead of iOS devices, Espresso is pure Android. Espresso is baked right into the Android SDK and integrated into Android Studio. Espresso has major benefits for teams looking to develop and test on Android devices. However, there are a few limitations to keep in mind. Let’s explore the pros and cons.

Pros

There are several major pros to using Espresso for your mobile automation testing:

• Espresso is 100% free to use
• Much like XCUITest, Espresso is fast. Since it is a native framework, baked right into Android SDK and integrated with Android Studios, and doesn’t require a server, Espresso can be much quicker than a solution like Selenium or Appium.
• Espresso’s core API is small and compact, making tests easy to maintain, change, and customize.
• With Espresso’s seamless UI synchronization, tests are less flaky and more intuitive with assertions.
• Espresso also offers Espresso Test Recorder that allows you to navigate through your application, add in assertions, and Espresso Test Recorder will help generate a scripted test. This helps quickly build test suites that can be modified later, as well as help learn Espresso scripting for the junior QE.
• Since Espresso is deeply integrated with Android, it also offers clear failure reporting and provides debugging information.
• Espresso can also be easily integrated into the CI/CD pipeline.

Cons

• Espresso is limited to Java and JUnit languages.
• Espresso is not compatible with iOS devices.
• Espresso is only for UI testing.
• You must have access to your Application’s source code
• Using Espresso (as well as the Espresso Recorder) does require some prerequisite basic knowledge of Android applications, including how they are built and how to create tests for them.
• Espresso has mostly been built with the Android Developer in mind, and is not near as QA-friendly as solutions like Appium.
• Espresso is pure Android and cannot help the team that needs to test both Android and iOS devices.

Appium

What is Appium?

Appium is an open-source automation framework, or collection of client “automation libraries” as Appium calls it, used primarily to test both Android and iOS native mobile applications, as well as hybrid and web applications. Appium is part of the Selenium WebDriver family, thus utilizes Selenium WebDriver API that specifies a client-server protocol that uses vendor-provided frameworks under the hood. With no need to compile a third-party framework or code, you’ll be able to deploy the same app you have tested across cross-platform devices with confidence.

Pros

There are several major pros to using Appium for your mobile automation testing:

• Appium is open-sourced and comes with a strong, supportive community to help facilitate your testing needs.
• Using native frameworks, such as XCUITest for iOS, UiAutomator or Espresso for Android, and WinAppDriver for Windows, Appium allows you to write tests against multiple platforms all in one sitting.
• Appium’s cross-platform accessibility and code reusability is extremely beneficial in mobile app automation and eliminates device fragmentation in your testing.
• Appium client libraries are available in most major languages, including Java, JavaScript, Python, C#, and Ruby. Along with supporting multiple frameworks, this allows you the freedom and flexibility to set up and manage your test environment however you see fit!
• Appium allows you to test on real devices and emulators/simulators with assisted setup and no extra dependencies needed.
• Appium comes with Appium Desktop for those who prefer to live outside the command line. Appium Desktop features include
  • Easily start/stop Appium server and view logs & screenshots
  • Appium Inspector allows you to view your app’s source tree: find any element and its locator within your application and perform basic interactions with them
  • Step Record: Record actions imposed on your application and let Appium auto generate code for said actions
• Appium supports end-to-end testing, including complicated gestures and behaviors for mobile applications.
• Appium can easily be integrated with the CI/CL pipeline
• Because Appium is the most popular framework used for mobile test automation, most Mobile Testing vendors have the most support for Appium, making Appium testing more convenient when using it alongside solutions that allow for real device access and Session Exploration.

Cons

• Appium is script-based that comes with its own learning curve, potentially challenging for the junior QE.
• Although Appium allows the freedom to manage your environment, environment setup can still be challenging, tedious, and time-consuming.
• Appium only offers real devices locally, making management of devices difficult if you’re in need of multiple, real devices.
• Appium performs slower test executions since it involves a remote webdriver, which applies potential network issues and processing command time.
• Appium scripting bears the issues of brittle and flaky tests resulting in instability, inconsistency, and involves more time in maintenance than development.

AI-driven Appium with Kobiton

While we believe that teams should choose whatever framework suits them best (and we will help make Appium, Espresso, and XCTest / XCUITest better), we have focused heavily on the Appium automation engineer. Way back in 2021, before the generative AI boom,  we released  what we called “AI-enhanced Appium,” which makes your Appium automation easier to author, more comprehensive in its coverage, faster in its execution (hallelujah!), and easier to remediate for when issues are encountered. This capability has been maturing in the market for several years, and Kobiton is still the only vendor that can generate an Appium script from a manual test. Test authoring with Kobiton AI-driven Appium automation

It all starts with test authoring. With Kobiton, we’ll let you inject our AI Engine into your existing Appium automation scripts, but we can also help you get to that script faster to begin with by leveraging our auto-Appium generation or Appium Export technology.

Kobiton’s Appium Export technology allows you to run a manual test on a Kobiton real device, tell our AI to auto-generate an Appium script, and then export that script into your IDE for quick “base script” authoring. Not only is this easy, but it’s also a huge time saver for teams who are trying to quickly build out their libraries of Appium automation.

Beyond just getting to your Appium “base script,” we also make it easy to author assertions into your Appium script including visual assertions. This allows you to take advantage of the Visual Assertions and Visual Testing capabilities previously unique to the Kobiton Scriptless Automation flow and easily inject them into your Appium scripts. And, unlike other solutions, Kobiton allows you to do this by simply making a quick change to your Desired Capabilities and also doesn’t require setting a new baseline for each and every mobile device. With Kobiton, you can run a Visual Test using one device’s visual output (let’s say a Samsung Galaxy S24) as a baseline and compare that baseline across multiple different device types (let’s say LG G7 and Motorola Edge ).

Yes, that means no more making API calls, no more source code instrumentation, and no more endless baseline screenshots.

Test execution with Kobiton AI-driven Appium automation

After the test is authored, it’s got to execute quickly. That’s why Kobiton offers “souped-up” Appium that can run greater than two times as fast as a standard Appium execution. In addition to this, injecting Kobiton’s AI into your script also allows for advanced adaptation and auto-correction capabilities that make your Appium much more reliable and stable when running in parallel across different device types.

Test remediation with Kobiton AI-driven Appium automation

Okay, so you’ve run our AI-driven Appium and it’s been able to run across a bunch of different devices while also invoking Visual assertions to capture visual issues and discrepancies.

Now what?

With Kobiton, you’ll actually be able to easily remediate those visual issues identified by Appium with our Assertion Overview and Remediation interface. With this interface, you can easily see where AI-augmented testing identifies visual discrepancies across device types and/or application versions, and you can even give it instructions on how to better execute your tests going forward with directions around the strict and relaxed comparison.

To see this all in action, check out this snippet of a “visual assertions in Appium” demo run by Leslie Tan, Global Director of Solutions Engineering at Kobiton:

AI-driven Appium Pros

• Teams can take existing Appiums scripts and inject AI-powered assertions without the need for complex scripting.
• Injecting assertions only requires changing certain Kobiton-specific desired capabilities’ values from “false” to “true”.
• Easily turn already-existing Functional test scripts into:
• Visual Tests
• Performance Tests 
• Crash identification tests 
• Accessibility Tests 
• Remediate issues raised by Kobiton’s assertions within the Kobiton remediation menu interface.
• Kobiton offers souped-up Appium that is >2-3x faster than normal Appium, making Appium on par with native frameworks like Espresso and XCUITest (both mentioned earlier).
• Insert Kobiton’s benefits into your already-existing scripts alongside existing parameterization and dynamic data.
• Kobiton’s Appium generations and Export capabilities make authoring Appium automation much easier.

AI-driven Appium Cons

• Unless users leverage the Kobiton Appium Export capability, creating Appium scripts from scratch requires technical know-how and time.
• Kobiton’s AI-assisted script-based approach only works for Appium, and does not yet support alternative frameworks, such as Espresso and XCUITest.

Wrapping up

There are many different test automation solutions out there, but only a handful that are truly optimized for mobile application automation. While we understand Kobiton’s offering as providing the most feature-rich, comprehensive, and flexible solution, we recognize that teams might have specific needs that fit better alongside other solutions. This is why we recommend taking a thorough look at your team’s make up, skill-set, and needs before evaluating and ultimately choosing a solution.

Are you ready to experience Kobiton? Request a demo today and see how we can help you revolutionize your mobile application development with AI-augmented development and testing tool.