10 Mobile App Testing Interview Questions and Answers for QA Engineers

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If you're preparing for qa engineer interviews, see also our comprehensive interview questions and answers for the following qa engineer specializations:

1. What aspects of mobile app testing do you consider when developing a test plan?

When developing a test plan for mobile app testing, there are several aspects that I consider to ensure comprehensive test coverage. These are:

  1. Device coverage: It is important to test the application on a variety of devices to ensure that it is compatible with different screen sizes, resolutions, and operating systems. In my previous role, I tested an e-commerce app on 20 different devices and found that the app crashed on 5 of them due to memory leaks. This helped our development team identify and fix the issue before it led to negative customer feedback.
  2. Network conditions: Mobile apps often require network connectivity to function properly. Therefore, it is important to test the application under different network conditions, such as 3G, 4G, and Wi-Fi to ensure that the app performs as expected. In a recent project, I tested a mobile banking app on 3G network to simulate real-world usage and found that the transaction processing time was longer than expected. We were able to optimize the server response time and reduce transaction processing time by 40%.
  3. Security: Mobile apps often handle sensitive user data, such as personal details, financial information, and passwords. Therefore, it is critical to test the app's security features thoroughly to ensure that user data is not compromised. In my current role, I performed penetration testing on a healthcare app and found several vulnerabilities that could have led to data breaches. We worked with the development team to implement industry-standard security measures, which resulted in a 75% improvement in the app's security score.
  4. Usability: The app should be intuitive and easy to use for the end-users. Therefore, it is important to perform usability testing to identify any user experience issues or usability barriers. For instance, in a fitness app, I found that workout tracking feature was not user-friendly and resulted in low user engagement. We redesigned the feature and tested it with a group of beta users, which resulted in a 50% increase in user engagement with the feature.
  5. Functional testing: Finally, it is important to test the app's functionality thoroughly to ensure that all the app features work as intended. I use a combination of manual and automated testing techniques to achieve maximum coverage. In my previous role, I tested a social media app's new feature of video sharing and found that the app crashed if a user shared videos longer than 5 minutes. We identified the issue during testing and fixed it before it impacted the users.

2. What tools have you used for mobile app testing?

During my previous role as a QA Engineer, I have utilized a variety of tools for mobile app testing. Some of the most useful tools I have used include:

  1. Appium: I have used Appium extensively for both iOS and Android app testing. The open-source tool is perfect for automating mobile app tests, which saves time and ensures accuracy. In my previous project, I used Appium to test a custom-built e-commerce app for iOS and Android, which helped identify more than 400 bugs before launching.
  2. Charles Proxy: I found Charles Proxy to be a useful tool for monitoring network traffic and debugging issues during mobile app testing. In one particular project, I was able to identify a significant server-side issue that had been slowing down the app's load time, which resulted in a 30% increase in app speed after fixing the issue.
  3. Xcode: As an Apple-developer, I utilized the built-in Xcode tool for iOS app testing. The interface allowed me to test app on various versions of Apple devices, and I could easily simulate different network conditions to identify potential connectivity issues.

Overall, my experience with various testing tools has given me a deep understanding of how different tools function in various contexts. I enjoy keeping up with the latest testing tool developments and integrating new approaches into my testing strategies.

3. Can you discuss a time when you encountered a particularly challenging mobile app bug and how you solved it?

During my time at XYZ Company, I encountered a particularly challenging bug in our mobile app. Users were reporting that the app would crash when trying to upload a photo through the app's camera feature.

  1. First, I took a deep dive into the app's code to try and identify the root cause of the problem. After examining the code, I found that there was an issue with the camera permissions not being properly requested.
  2. Next, I worked with the development team to implement a fix for the issue. We updated the code to request all necessary permissions before allowing the user to take a photo through the app.
  3. After the fix was implemented, I conducted thorough testing of the app to ensure that the issue had been properly resolved. I tested the camera feature on multiple devices and was able to successfully upload photos without experiencing any crashes.

As a result of this bug and the fix I implemented, user complaints about the app crashing decreased by 50% within the first week. This not only improved the user experience but also helped to increase user retention.

4. How do you ensure compatibility across multiple mobile devices and platforms?

One of the key challenges of mobile app testing is ensuring compatibility across multiple devices and platforms. To achieve this, I follow a rigorous testing process that includes:

  1. Researching the most popular devices and operating systems being used by our target audience. This includes analyzing market share data and gathering feedback from our users.
  2. Creating a comprehensive test plan that covers all the different device and platform combinations.
  3. Using cloud-based testing tools like BrowserStack or Sauce Labs to test our app on hundreds of real devices and configurations in the cloud. This enables us to test for compatibility across various operating systems, browsers, and device types without needing to physically own every device.
  4. Conducting manual testing on a subset of devices to ensure the app behaves as expected on each device. This includes checking for differences in device performance, screen resolution, and network connectivity.
  5. Automating test scripts using tools like Appium or Selenium to ensure consistent, repeatable testing of our app on multiple devices and operating systems. This helps us catch bugs early on and significantly speeds up the testing process.
  6. Working with the development team to analyze any compatibility issues that arise and prioritize them based on severity and impact on users.
  7. Keeping up-to-date with new devices, operating systems, and browser versions to ensure our app continues to work seamlessly across all platforms.

By following this process, I have successfully ensured compatibility across multiple mobile devices and platforms for several apps. For example, when testing a fitness app, I used cloud-based tools to test the app on over 100 devices and configurations, resulting in a significant increase in user satisfaction and a 20% increase in app downloads.

5. Can you walk me through your experience with automated mobile testing?

I have extensive experience with automated mobile testing. In my previous role as a QA Engineer at XYZ Company, I implemented an automated mobile testing framework which significantly reduced our testing time and increased the overall quality of our mobile applications.

  1. Firstly, I evaluated several testing frameworks and tools before deciding on Appium, as it provided the necessary support for both Android and iOS platforms.
  2. Next, I worked closely with the development team to understand the codebase and identify the most critical test cases.
  3. Then, I wrote automated tests to cover these critical test cases using Appium and Selenium WebDriver. These tests were integrated with the continuous integration pipeline to ensure that they were executed on every code push.
  4. Throughout the testing process, I kept track of test coverage, performance metrics, and bug reports. This allowed me to identify and fix issues quickly while continuously improving the overall test coverage.

The automated testing framework I implemented at XYZ Company resulted in a 30% reduction in the testing time and a 40% improvement in bug detection rate. Additionally, the framework provided more reliable results and freed up valuable QA resources, allowing us to focus on other areas of testing such as exploratory testing and user acceptance testing.

6. When would you consider it necessary to conduct manual mobile testing?

Manual mobile testing is necessary when automated testing is not enough to cover all the possible scenarios that a user might experience while using the mobile application. Manual testing allows the QA engineer to identify the issues that automated tools might miss, such as usability, compatibility and visual issues.

  1. Usability is one of the main factors that can't be tested by automation tools. Manual testing helps identify how easy it is for users to navigate the application, whether the buttons are in the right place, and ensures that the app follows industry standards.
  2. Compatibility must be tested manually through a variety of devices, operating systems and browser configurations. Automated testing tools cannot cover all of these scenarios.
  3. Visual issues can be identified through manual testing, such as graphical glitches or layout problems. It's also easier to spot areas where the color contrast is low or the font size is too small, making it difficult for users to read the content. This is one of the areas where manual testing is absolutely necessary.

Manual testing, when used in conjunction with automated testing, has always been a proven method of ensuring that the mobile application is well-tested and of high quality. Based on my experience, manual testing has significantly improved the quality of mobile applications by detecting bugs that automation tools may have missed. It's also the only way to identify usability, compatibility, and visual issues.

7. What metrics do you track during mobile app testing?

As a QA Engineer, I track several metrics during mobile app testing. These metrics help me to identify and resolve issues with the app as quickly as possible. Here are the metrics that I track during mobile app testing:

  1. App launch time: I measure how long it takes for the app to launch from the moment the user clicks on the app icon. In my previous project, I managed to decrease the app launch time by 30% by optimizing the app's code.
  2. App response time: I measure how long it takes for the app to respond to user inputs such as button clicks or swipes. In a past project, I decreased the app response time by 40% by implementing a more efficient algorithm.
  3. Battery usage: I monitor the app's battery usage to ensure that the app is not draining the user's battery excessively. In a previous project, I reduced the battery usage by 20% by optimizing the background processes that the app was running.
  4. Memory usage: I track the app's memory usage to ensure that the app is not using too much memory and causing crashes or slowing down the user's device. In another project, I managed to reduce the app's memory usage by 25% by optimizing the app's data structures.
  5. Error rates: I monitor the app's error rates to identify and fix any issues that are causing the app to crash or malfunction. In a recent project, I decreased the error rate from 5% to 0.5% by fixing several issues related to memory leaks and null pointer exceptions.

These metrics are essential to ensuring that the mobile app runs smoothly and provides an optimal user experience. By tracking these metrics, I can quickly identify and rectify any issues in the app, resulting in a better user experience and increased user satisfaction.

8. How do you test for app security and data protection?

When it comes to testing for app security and data protection, I like to utilize a variety of methods to ensure that the app is as secure as possible. One of the first things I look at is the encryption used to protect sensitive data in transit and at rest. I check to make sure all sensitive data is encrypted and that the encryption methodology used is known for its high level of security.

  1. I also check the overall architecture of the app to ensure that security is built in from the ground up. This includes reviewing the codebase to confirm that best practices are being followed and that any vulnerabilities are addressed immediately.
  2. One tool that I use to test app security is OWASP ZAP, which is a penetration testing tool that is specifically designed to find vulnerabilities in web applications. By running this tool against the app, I can identify any potential vulnerabilities and work with the development team to address them.
  3. Another method that I use to test for security is to conduct a threat modeling exercise. This involves identifying potential threats to the app and its data and then developing strategies to mitigate those threats.
  4. Finally, I run regular security audits and tests to identify any new vulnerabilities that may have been introduced as new features are added or as the app continues to evolve over time. By being proactive and vigilant, we can stay one step ahead of potential attackers and ensure that our users' data is always protected.

By employing these methods, I have been able to help increase app security and reduce the risk of data breaches or other security incidents. For example, in my last position, after implementing regular OWASP ZAP scans and threat modeling exercises, we were able to identify and address several critical vulnerabilities before they could be exploited by attackers. This resulted in a 50% reduction in the number of security incidents reported by our users.

9. What steps do you take to ensure mobile app performance?

As a QA Engineer, there are several steps that I take to ensure that the mobile app performance is at its peak. Firstly, I conduct functional testing on the app to ensure that all features included in the app work as intended. This includes making sure that the app is responsive and its interface is visually appealing to users.

  1. When testing the app, I pay close attention to the application's load times. I do this by using various tools such as JMeter, as well as checking the app's performance on various devices to see how it handles different types of loads. For instance, in my previous role, I used JMeter to test a fitness app, which resulted in a 57% decrease in load times. This improvement increased the user engagement by 24%.
  2. I also optimize the app's code and database by checking for SQL query optimization problems that may cause lags in performance. This includes updating queries and checking response times for data requests. In my previous role, I identified and fixed a query optimization problem that was slowing down a retail app's database. The fix increased the app's speed by 35% and resulted in a 12% increase in user retention rates.
  3. Finally, I make sure to communicate with developers about any issues that I find so that they can be fixed before the app is released to the public. This saves time, minimizes the risk of negative reviews and feedbacks and ensures a user experience that is free of hindrance.

Overall, by conducting functional testing, using performance tools, optimizing code and databases, and proper communication with the development team, I have been able to enhance mobile app performance efficiently. These steps reflect my work experience and produce excellent results in increasing app performance and minimizing negative reviews.

10. How do you approach testing for native apps versus hybrid or web apps?

When it comes to testing, my approach differs depending on whether the app is native or hybrid/web. For native apps, I prioritize testing on actual devices that closely match the intended user base. This approach allows me to test for any hardware or software dependencies that may impact the user experience. Additionally, I conduct thorough testing of the app's user interface (UI) and user experience (UX) to ensure it meets high standards.

For hybrid or web apps, I use a combination of real mobile devices and emulators. One of the benefits of testing hybrid or web apps is the ability to test on multiple platforms within the emulator environment. This allows me to assess application performance and stability across a range of operating systems and iterations, as well as identify potential software conflicts.

To give you an example, during my work at XYZ Company, I was part of the quality assurance team for a mobile app that combined both native and hybrid components. Our team conducted extensive testing on multiple devices with different versions of iOS and Android operating systems to ensure that the app was optimized for all of our target clients. This approach resulted in a 75% reduction in reported bugs and generated positive feedback from customers regarding the app's ease of use and stability.


In conclusion, these 10 mobile app testing interview questions with answers for QA Engineers will help you prepare for your next job interview in the QA field. However, this is just the beginning of your job search. To stand out as a top candidate, we recommend that you write a great cover letter here, and prepare an impressive quality assurance testing CV here. Additionally, if you're searching for a new job, be sure to check out our remote Quality Assurance Testing job board for the latest job postings. Good luck with your job search!

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