Appium is an open-source mobile automation framework that helps to automate app testing for native, mobile web, and hybrid apps. Appium supports test automation on iOS mobile, Android mobile, and Windows desktop platforms. Appium is a service-based solution that helps to scale app testing for various devices and environments quickly. It functions like a virtual server that sends commands to device-native frameworks for scalable test automation. It is a cross-platform and cross-technology mobile test automation framework. Appium is also platform agnostic; that is, with minimal changes, you can automate testing for both iOS and Android apps using the same test scripts.
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Appium provides support for various programming languages to write test code. Hence, it offers excellent flexibility to test engineers to write test scripts in the desired programming language, Python, Ruby, Java, JavaScript, PHP, or more. It also enables testing an application system on real devices, emulators, and simulators. One can attribute the robust performance of Appium to the JSON Wire Protocol, which facilitates the communication between the Appium client and server for interacting with mobile devices. Once you familiarize yourself with various nuances to operate the Appium tool, it will help you quickly and effectively execute the automated tests.
What is Appium Driver?
The essential components of Appium architecture include the Appium server, Appium client libraries, JSON Wire Protocol, and Appium driver. Since Appium supports cross-platform testing, it uses multiple drivers for effectively managing various platforms. It utilizes multiple drivers to API (application programming interface) into automation sessions for corresponding platforms.
- UiAutomator2: For Android device testing, UiAutomator2 is the default Appium driver.
- UiAutomator1: It is the Appium driver for older android versions.
- XCUITest: It is the Appium driver for iOS device testing.
- WinAppDriver: It is the Appium driver for windows device testing.
- Espresso: Espresso is the new Appium driver to support Android device testing.
Appium Driver inherits from the Remote WebDriver class and adds various other functionalities to facilitate test automation through the Appium server. The Android Driver class inherits from Appium Driver, and testers must use this driver class only when initiating a test on an Android device or Android emulator. iOS Driver class inherits from Appium Driver and must be used when testing on an iOS device or iOS emulator.
What Is Appium Espresso Driver?
Appium has its own Appium Espresso driver to support the Espresso automation technology. The driver initiates an Espresso run on a device with its automation server that comes within the Espresso test APK package. Appium communicates with this automation server for triggering Espresso commands to forward the Appium client calls. Espresso is the newest Android driver that is based on Google’s Espresso technology. The Espresso driver operates in the scope of the W3C WebDriver protocol and consists of various custom extensions to cover OS-specific scenarios. The Espresso package generally includes two essential components.
- The driver part (which is written in Node.js) helps ensure communication between the Espresso server and Appium. It also consists of multiple handlers that use ADB or other system tools without communicating with the server.
- The server part (which is written in Kotlin with some features of Java) runs on the AUT and carries out the transformation of REST API calls into low-level Espresso commands.
UiAutomator2 Driver is a black-box testing framework, whereas Espresso Driver is a “gray-box” testing framework. The Espresso framework for Android was created as a “gray-box” testing framework. Gray-box testing combines both white-box testing and black-box testing. It is an automated UI testing framework (“black-box”), but it can also access the internals of an app (“white-box”). Hence, the Espresso framework opens up new testing opportunities, which was not possible with the UiAutomator2. The various possibilities Espresso framework opens up include:
- Access to the internal app code: The access to the application’s internals under test enables the QA to use arbitrary methods defined within the Android app.
- Less flakiness in App testing: Appium Espresso framework uses ‘Idling Resource’ that blocks the UI thread until it’s idle. It helps to reduce flaky tests in automation testing. A flaky test is a test that may pass and fail periodically without any code changes.
- Find elements off-screen: UiAutomator2 faces constraints when selecting elements present within the viewport. Espresso’s ‘on Data’ matcher helps to target the elements off-screen better.
How Drivers Work?
Within the Appium infrastructure, the Drivers are one of the most critical components. It is the responsibility of the driver to turn Appium API (WebDriver Protocol) into automation for a given platform. Drivers translate Appium client commands to the necessary information to automate app testing. Each driver within itself is a standalone WebDriver-compatible server. Drivers have a complex internal architecture, though each driver can set up its architecture in any way it prefers.
To Conclude:
Appium drivers are an essential component of the Appium architecture and support its client-server infrastructure. It enables the Appium testing tool to deliver robust performance, making automation testing more accessible and practical once you get through the learning curve.
About The Author
Nicole Hinton
Nicole is a freelancer & passionate blogger. She has 4+ years of experience in digital marketing and specialize in content writing, content marketing and organic search engine optimization. She has worked with many brands from Canada as well as the USA. Currently, she manages content marketing team of freelancers and doing their business efficiently.
