📱 Mobile QA interview prep

// WHO THIS IS FOR

For engineers interviewing for roles focused on iOS and Android quality — covering functional and exploratory testing on real devices, Appium automation, device matrix strategy, and the mobile-specific failure modes that web testers rarely encounter. Covers mid-to-senior scopes where the interviewer expects you to own device coverage decisions, not just execute scripts.

// SKILLS INTERVIEWERS EXPECT

Green = most frequently tested

// TYPICAL INTERVIEW ROUNDS

1. 1

   Mobile fundamentals

   30–45 min questions on native vs hybrid vs progressive web app differences and how the technology stack affects test approach. Covers the mobile test pyramid (unit, integration, UI), iOS vs Android tooling differences, real device vs emulator trade-offs, and how you decide which device types and OS versions to include in a test matrix. Interviewers assess whether you understand mobile-specific failure modes — not just transposing web testing instincts onto a phone.

2. 2

   Device strategy and test design

   Given an app description and a device farm budget, design a device matrix: how to prioritise OS versions, manufacturers, and screen sizes for maximum coverage with minimum redundancy. Extends to test cases for gestures (swipe, pinch, long-press), system interrupts (incoming call mid-flow, low battery alert, permission prompt), and network condition changes (3G → Wi-Fi handoff, offline mode). Interviewers look for structured risk reasoning, not just 'test on as many devices as possible'.

3. 3

   Appium automation or exploratory device task

   Write or review an Appium test for a login or navigation flow: DesiredCapabilities, element location (UiAutomator2/XCUITest selectors, accessibility IDs), action chains, and assertion strategy. Alternatively, you may be given a real device or emulator and asked to explore a feature for 20–30 minutes, then report findings structured as bug reports. Interviewers grade stable locator choices, handling of async app states, and the quality of any defects found.

4. 4

   Behavioural

   Situational questions — a test that passes on emulator but fails on real device, a device farm that introduces flakiness unrelated to the app, a device matrix that grows faster than the team can maintain. Also covers how you communicate fragmentation risk to product managers, how you coordinate with mobile developers on testability (accessibility IDs, deep link support), and how you balance automated coverage against the exploratory sessions that catch the bugs automation misses.

// TOPICS TO STUDY

• Native vs hybrid vs PWA: how the stack affects locator strategy, gestures, and tool choice
• Appium architecture: DesiredCapabilities, UiAutomator2 and XCUITest drivers, Appium Inspector
• Element location on mobile: accessibility IDs, XPath, UI Automator text matchers — stability trade-offs
• Real devices vs emulators/simulators: coverage, speed, flakiness, and cost trade-offs
• Cloud device farms: BrowserStack App Automate, Sauce Labs, Firebase Test Lab — parallelism and reporting
• Gesture testing: Appium W3C Actions API for swipe, pinch, long-press, scroll-to-element
• OS fragmentation: building a risk-weighted device matrix across iOS and Android versions
• Mobile performance indicators: startup time, frame rate drops, memory pressure, battery drain signals
• App lifecycle and interrupts: background/foreground transitions, incoming calls, permission dialogs mid-flow

// READINESS SELF-CHECK