Mobile Testing Interview Questions for Software Testing

Native apps are built for one platform and use device features fully, so testing focuses on OS versions, device features, install and update. Hybrid apps wrap web code in a native shell, so you test both the web view rendering and the native bridges like camera access. Mobile web apps run in a browser, so testing is closer to cross-browser and responsive testing. All three need network, screen size and performance checks.

An emulator imitates both the hardware and software of a device, as with the Android emulator, so it behaves close to a real phone. A simulator imitates only the software environment, as with the iOS simulator, and does not reproduce the hardware. Both are free and fast for early testing. Real devices are needed for camera, battery, sensors, actual performance, network behaviour and final sign-off.

Interrupt testing checks how the app behaves when something interrupts it: an incoming call, SMS, notification, alarm, low battery warning, network change, plugging in a charger or switching to another app. The app should pause correctly, keep the user's data and resume where the user left off. For example, a call during a payment must not cause a double charge or lose the transaction state.

Mobile users have many screen sizes, resolutions, notches and foldable screens, and they rotate their phones. Rotation can recreate the screen and lose entered data if not handled. Test portrait and landscape on key screens, small and large phones and tablets, and check text does not cut off, buttons stay reachable and the keyboard does not hide input fields. Check entered form data survives rotation.

Install a fresh build and verify first-launch screens and permissions. Test install with low storage. Update from the previous production version and check that login, settings, saved data and offline content are kept and migrations work. Test a forced update prompt if the app has one. Uninstall and reinstall, and confirm local data is cleared while server data returns after login. Check the app size is reasonable.

Model answer: Most users in India now use services first on their phones, so mobile quality directly affects customers. In my project I tested a college event app on four phones and found that the registration button was hidden by the keyboard on small screens. Fixing it raised sign-ups. I enjoy the variety of devices, networks and real-life situations that mobile testing involves.

Switch the device to dark mode and check every screen: text must remain readable, icons and images visible, and no white flashes during navigation. Switch back while the app is open. Then increase the system font size to the largest setting and confirm text does not overlap or get cut off and buttons remain usable. Also test display size or zoom settings and both orientations.

Test on real devices and OS versions, interrupts such as calls, battery, network changes, gestures, permissions and app store guidelines.

Check that the app asks for permission only when the feature is used, with a clear reason. Test allow, deny, and deny with do not ask again. When denied, the app must not crash and should explain how to enable it in settings. Revoke permission from settings while the app is in background and return. Test allow only once or only while using the app options on newer OS versions.

Verify notifications arrive when the app is in foreground, background and closed. Check title, text, icon and that tapping opens the right screen with the correct data. Test with notifications disabled at OS level and inside app settings. Check behaviour after logout, reinstall and on multiple devices with the same account. Test grouping of many notifications, time-sensitive ones, and that no notification shows private data on the lock screen.

It checks app behaviour on different networks: Wi-Fi, 4G, 5G, slow 2G or 3G, high latency, packet loss and no network. Also test switching between Wi-Fi and mobile data in the middle of an action, and airplane mode. The app should show loaders and clear offline messages, retry safely without duplicate actions and not freeze. Network throttling tools in developer options or proxy tools help simulate these conditions.

Run typical user sessions on a real device and measure battery drain, CPU and memory with platform profiling tools or the device's battery statistics. Compare with the previous version. Look for background work continuing after the app is closed, GPS left on, frequent network polling and memory that keeps growing, which signals a leak. Test on low-RAM devices too, where the OS kills heavy apps quickly.

A deep link opens a specific screen inside the app from a URL, email, SMS, QR code or notification. Test that each link opens the correct screen with the right data when the app is installed, closed or running in background. If the app is not installed, it should open the store page or a web fallback. Test links that need login, expired or invalid links, and that parameters cannot be tampered with to access other users' data.

Android has many manufacturers, screen sizes and OS versions with custom skins, so device fragmentation and background-kill behaviour need more coverage. iOS has fewer devices but strict permission, privacy and store review rules. Navigation differs: Android has a system back button or gesture, iOS relies on in-app navigation and swipe back. Notification, permission and file-access behaviours also differ, so test cases need platform-specific steps.

Enable developer options and USB debugging, connect the phone and confirm it is visible with adb devices. Clear old logs with adb logcat -c, reproduce the bug, then save logs with adb logcat -d > crash_log.txt, filtering by the app package or error level if needed. For a crash, search for FATAL EXCEPTION. Attach the log, device model, OS version, app version and a screen recording to the bug.

Turn on the screen reader, TalkBack on Android or VoiceOver on iOS, and check every button, image and field has a meaningful label and the reading order is logical. Check text scales with system font size, colour contrast is sufficient and touch targets are large enough, about 48 by 48 density-independent pixels. Make sure information is not shown by colour alone and that the app works without complex gestures.

Test enabling biometrics in app settings after a password login. Verify login with a registered fingerprint or face, and failure with an unregistered one, falling back to PIN or password after the allowed attempts. Remove or add a fingerprint in device settings and check the app asks for re-authentication. Test devices without biometric hardware, disabled biometrics and app behaviour after an OS update or reinstall.

Test with location permission allowed, denied and approximate only. Use mock location tools to simulate different cities and moving routes. Verify the app shows nearby results correctly, updates location while moving and handles GPS turned off. Check accuracy indoors and with weak GPS, battery impact of continuous tracking and that background location is used only if needed and explained to the user.

Check that the form data is still there when the user returns after a few seconds and after a longer time. Test when the OS kills the app in background due to low memory, which you can force with developer options, and confirm the app restores state or at least warns the user. Also check session timeout behaviour and that sensitive screens are hidden in the recent apps view if required.

Model answer: Situation: users of one budget phone model reported that the camera upload screen was black. Task: reproduce it. Action: I borrowed the same model, found the issue only appeared when the battery saver was on, and logged the bug with the device model, OS version, logs and a video. Result: the developer fixed the camera initialisation, and we added that model to our device matrix.

Fill the device storage close to the limit, then install or update the app and confirm a clear message if it cannot proceed. Inside the app, try downloads, photo capture, caching and saving drafts. The app should show a helpful error, not crash or corrupt data. Also check what happens to the local database when a write fails, and whether the app recovers after space is freed.

Android phone makers ship their own skins and settings on top of Android, so the same app can behave differently. Common problems are aggressive battery savers that kill background tasks and delay notifications, different permission screens, custom fonts and display scaling, camera differences and modified WebViews. Pick devices from the brands most used by your audience and test background work, notifications, camera and layout on each.

Appium is an open-source tool for automating native, hybrid and mobile web apps on Android and iOS using the WebDriver protocol. Tests can be written in Java, Python, JavaScript and other languages, and it uses platform drivers such as UiAutomator2 for Android and XCUITest for iOS. It can run on emulators, simulators, real devices and cloud device farms. Stable accessibility IDs make the best locators for it.

Use the app's analytics, or market data if it is a new app, to find the top devices, OS versions and screen sizes. In India, cover a strong share of budget and mid-range Android phones with low RAM, a few manufacturers' custom Android skins, the two or three latest Android versions, and recent iPhones if iOS is supported. Add a tablet if relevant. Review the matrix each quarter and use a cloud device lab for wider coverage.

Reproduce it on that exact OS version, using a real device or an emulator image, and note the device model and app build. Capture the crash log and stack trace. Check if the code uses an API or library not supported on that version, or a permission or storage behaviour that changed. Log the bug with logs and the minimum supported version from the requirement, so the team can decide to fix it or raise the minimum version.

Use the platform's sandbox or test accounts so no real money is charged. Test a successful purchase, cancellation, payment failure, pending payment, refund and restoring purchases on a new device. For subscriptions, test free trial, renewal, upgrade, downgrade, expiry and grace period, often with shortened test durations. Verify the server records the purchase and unlocks features, and that killing the app mid-purchase does not lose it.

Turn off the network and perform supported actions, such as creating, editing and deleting records, and check they are saved locally with a pending status. Reconnect and verify everything syncs once, in order, with no duplicates. Test conflicts, where the same record is changed on two devices, and confirm the agreed rule applies. Test sync after app restart, on a slow network and when the server rejects a change.

A cold start launches the app from scratch when it is not in memory, loading the process and the first screen; it is the slowest. A warm start happens when the app process exists but the screen must be recreated, and a hot start just brings it to the foreground. Users abandon slow apps, so teams set targets, such as cold start under two seconds on a mid-range device, and measure each release for regressions.

Check that sensitive data like tokens and personal details are not stored in plain text on the device or written to logs. Verify all traffic uses HTTPS and the app rejects invalid certificates. Check session timeout, logout clearing data and that sensitive screens block screenshots if required. Test behaviour on rooted or jailbroken devices if the policy needs it, and that API keys are not visible in the app package.

Collect details from reviews and support: devices, OS versions and app version when it started. Compare battery usage of the current and previous versions on the same devices over a typical session and while idle in background. Use profiling tools to look for background location, wake locks, frequent sync or network polling. Share measurements with developers, verify the fix with the same method, and add a battery check to release testing.