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Functional Testing for Native Mobile Apps: iOS and Android

Mobile app developers must perform functional testing to ensure the app works properly and meets requirements. This testing checks the user interface, databases, APIs, security, and other application features to ensure they work for users. Automation testing simulates user scenarios to provide an app that works, is bug-free, and is user-friendly.

Functional testing is crucial to mobile app development. It ensures the app meets regulatory and market standards and identifies user experience issues. Testing ensures app quality, user satisfaction, and market success in a competitive market.

What is Functional Testing?

Software systems are validated against functional requirements/specifications through a type of testing called functional testing. Functional testing aims to test each software application function by providing appropriate input and verifying output against functional requirements. This testing checks the application’s user interface, APIs, databases, security, client/server communication, and other functionality to ensure compliance.

Objectives of Functional Testing

Here are some objectives of functional testing – 

  • To Check the Accuracy of Functions

Make sure that every app function performs under the parameters that have been specified.

  • To Make Sure User Needs are Satisfied

Verifying that the program operates as anticipated and meets all user needs.

  • To Find Defects

Finding any mistakes or malfunctions in the application’s operation before the product’s release.

  • For Quality

Ensuring the product works as intended in various scenarios improves quality.

Challenges Involved in Functional Testing

Native mobile app functional testing is challenging, particularly in the context of the iOS and Android ecosystems. These challenges include:

  1. Device Fragmentation: It is challenging to guarantee app performance across the wide range of devices available on the market, each with a unique screen size, resolution, and hardware setup.
  2. Versions of Operating Systems: The operating systems on the iOS and Android platforms are regularly updated. Testing the app across OS versions is necessary because each new version may affect app functionality.
  3. User Interaction: Native apps use mobile devices’ accelerometers, GPS, cameras, and touch gestures. Understanding how these interactions should work on each platform is necessary for testing.
  4. Network Conditions: Mobile apps are often used in varying network conditions. Functional testing must account for these variations to ensure app performance in different connectivity scenarios, including offline mode.
  5. Platform-Specific Guidelines: There are distinct design and functionality guidelines for iOS and Android. To ensure a smooth user experience, apps must follow these rules, so testers must know the requirements specific to each platform.

Functional testing must be strategic, using specialized tools and frameworks, understanding platform-specific nuances, and testing across devices and OS versions. Native mobile app developers can overcome these challenges to provide a reliable, high-quality experience on any device or platform.

See also  Achieving Functional Consistency Across Different Devices And Resolutions

Functional Testing vs. Other Testing

Here are the differences between functional and other testing: 

  1. Unit Testing: Examining each code component to ensure it functions as intended. Functional testing ensures the application meets requirements by testing its entire or partial functionality.
  2. Integration Testing: Functional testing assesses application requirements, while integration testing investigates module data communication. It checks integration points and data flow between modules to ensure compatibility.
  3. System Testing: The complete and integrated software product is tested to meet requirements. System testing includes performance, security, and usability; functional testing focuses on functionality.  
  4. User Acceptance Testing (UAT): End-users test the system for functionality and deployment readiness. Functional testing is more technical and done by testers during development, while UAT is the final testing before the product goes live.


Functional Testing’s Importance for Strong User Experience

To guarantee a top-notch user experience, functional testing is essential because it:

  • Ensuring Reliability: Functional testing ensures the application is dependable and performs as intended by confirming that each function runs under the requirements specifications.
  • Enhancing Usability: By testing the application from the user’s viewpoint, usability issues can be found and fixed, resulting in a more intuitive and user-friendly interface.
  • Minimizing Bugs and Errors: Functional testing helps identify defects early on, which results in fewer bugs and glitches when the app is released, making the user experience more seamless.
  • Increasing Customer Satisfaction: More customer satisfaction and loyalty result from an app that meets user expectations and operates well.

Challenges of Functional Testing for Mobile Apps

Mobile app functional testing presents a distinct set of difficulties that can significantly affect the efficacy of the testing plan. Understanding these challenges is essential for creating a thorough testing plan that ensures app functionality across all target devices and platforms.

  • Device Fragmentation

One of the most significant challenges in mobile app testing is device fragmentation. The market has many devices with different screen sizes, resolutions, hardware capabilities, and specifications. 

This diversity means that an app might perform well on one device but encounter issues on another due to differences in hardware or screen dimensions. Ensuring consistent app functionality across this wide array of devices is daunting for testers.

  • Operating System Versions

IOS and Android platforms frequently release new operating system versions while older versions remain used by many users. Each version may have features and bugs affecting app functionality. Testing an app across multiple OS versions is essential to ensure a stable and consistent user experience for all users, regardless of their OS version.

  • User Interaction Methods

Mobile devices offer various user interaction methods, such as touch gestures (tap, swipe, pinch), device orientation changes, and hardware buttons. These interactions can vary significantly between devices and must be thoroughly tested to ensure the app responds correctly. 

Additionally, the app must be tested under different conditions, such as the low battery, interruptions by calls or notifications, and connectivity changes, to verify its robustness and resilience.

See also  Functional Testing for Single-Page Applications

Differences in Testing Requirements Between iOS and Android Platforms

Here are some differences in testing requirements between iOS and Android platforms – 

  • Platform-Specific Guidelines

Apps must meet iOS and Android design and operational guidelines to be accepted in their stores. To comply with Apple’s Human Interface Guidelines and Google’s Material Design principles, apps must be tested differently on each platform.

  • Development and Testing Tools

The tools available for development and testing on iOS and Android differ. iOS developers and testers often use Xcode and XCTest, while Android developers might use Android Studio along with Espresso or UI Automator. These platform-specific tools require testers to have specialized knowledge and skills to effectively est apps on each platform. 

  • Deployment and Update Cycles

App deployment and updating differ between platforms. Apple reviews iOS apps, affecting update frequency and ease. 

The more open Android ecosystem allows faster updates and changes how users receive and accept updates. Testing strategies must consider these differences to ensure timely updates and bug fixes.

  • Security and Permissions

iOS and Android handle app permissions and security differently. Testing must ensure the app correctly requests and handles permissions on both platforms, respecting user privacy and platform security guidelines. This includes testing for scenarios where permissions are denied or revoked.

Tools and Frameworks for Functional Testing of Native Mobile Apps

Various tools and frameworks, each with features and best use cases, support functional testing of mobile apps. These tools ensure app functionality across devices and operating systems. 

The most popular iOS and Android tools and frameworks are listed below.

For iOS: 


  • Apple offers XCTest, a testing framework for creating UI, performance, and unit tests for iOS apps using Xcode.
  • It supports the TDD (Test-Driven Development) and BDD (Behavior-Driven Development) approaches and easily integrates with Xcode. It simplifies writing and running tests, including asynchronous networking code tests.
  • XCTest is a native solution for developers and testers who want to write and run tests on macOS, iOS, watchOS, and TVOS.


  • XCUITest, an extension of XCTest, makes iOS app UI testing possible. It allows testers to behave as users would and interact with the user interface elements of the app.
  • It provides a powerful and intuitive API for UI testing, including recording UI interactions to generate test scripts. Its integration with Xcode also allows automated testing to be part of the CI/CD pipeline.
  • XCUITest is ideal for testing the UI and functionality of iOS apps, especially for automating user interaction scenarios and regression testing.


  • The open-source Appium test automation framework allows for testing mobile web, hybrid, and native apps for iOS and Android.
  • It supports Java, Ruby, Python, and JavaScript programming languages. Appium interacts with the app using the platform’s accessibility features without changing the code.
  • Appium is best for teams that need a cross-platform testing solution that works with multiple programming languages and development environments. 

For Android:


  • Espresso is a testing framework that Google offers for creating concise, trustworthy UI tests for Android apps.
  • Espresso automatically synchronizes test actions with the app’s UI, ensuring that tests are not flaky. It also has a rich API for asserting UI component states.
  • Espresso is perfect for developers and testers who need a powerful UI test tool that works with Android Studio and Gradle.
See also  Achieving Functional Consistency Across Different Devices And Resolutions

UI Automator

  • A UI Automator testing framework offers a collection of APIs for creating UI tests that simulate user interactions on Android smartphones.
  • It supports testing apps across apps and system settings, making it suitable for testing multiple apps or the Android system. UI Automator simulates system and app user actions.
  • UI Automator is best used for testing the UI of Android apps in situations where interactions with system components or multiple apps are required.

Appium (for Android)

  • Appium’s capabilities extend to Android, making it a versatile tool for cross-platform testing.
  • It benefits teams working on iOS and Android apps, allowing test scripts to be reused across platforms.

Mobile app developers and testers can benefit from these tools, frameworks’ strengths, and ideal use cases. Project requirements, such as target platforms, app complexity, and the development environment, often determine tool selection.

Cross-browser platforms are essential for functionally testing iOS and Android native apps. Developers and testers can use these platforms to ensure an app provides a high-quality user experience across devices, browsers, and operating systems. 

These platforms are essential due to the variety of mobile devices and operating systems, especially Android. They enable device testing in various conditions without physical access. This saves time and resources and significantly expands the testing process’s coverage, ensuring that apps perform well regardless of the user’s device or browser.

One such platform that facilitates comprehensive and efficient cross browser testing and web application testing is LambdaTest. LambdaTest is an AI-powered test orchestration and execution platform that lets you run manual and automated tests at scale with over 3000+ real devices, browsers, and OS combinations. It allows you to perform automated and manual testing of your web and mobile applications across various browsers and real mobile devices. 

By leveraging LambdaTest, teams can identify and fix compatibility issues faster, ensuring a seamless user experience across all platforms and devices. The platform supports a wide range of testing types, including functional testing. It offers integrations with numerous development and testing tools, making it a versatile choice for teams aiming for high-quality native mobile app development.


As discussed in this blog, functional testing is essential to creating high-quality native iOS and Android mobile apps. We have examined mobile functional testing challenges like device fragmentation, OS versions, and user interaction methods.  

We have also discussed iOS and Android testing requirements and introduced popular tools and frameworks like XCTest, XCUITest, Appium, Espresso, and UI Automator to address these issues.

Functional testing is crucial to creating high-quality native mobile apps.  It ensures apps meet functional requirements and provides a smooth, bug-free user experience. As mobile app development evolves, functional testing tools, trends, and practices must be updated. Teams seeking to improve their testing and ensure app compatibility across devices and platforms can benefit from platforms like LambdaTest.

Developers and testers can improve mobile app quality and reliability by using these insights and resources, increasing user satisfaction and success in the competitive app market.