Software Testing Interview Questions for Consulting Companies

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Verify inserted, updated and deleted rows match UI actions, check constraints, duplicates, NULLs and totals with COUNT and SUM queries.

What is boundary value analysis?

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Testing at the edges of input ranges, such as 17, 18 and 19 for an age limit of 18, since errors cluster at boundaries.

The UI shows the correct order total, but the database has a different value. What do you check?

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Note the order ID and compare the UI value, the API response and the database value to find where they differ. Check if the UI calculates the total on the screen instead of using the saved value, whether taxes, discounts or rounding are applied at different layers and whether a later update job changed the record. Log the bug with all three values, because invoices and reports will use the database figure.

How would you test rate limiting on a public API?

Agile, SQL and API TestingHard

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Find the documented limit, for example 100 requests per minute per key. Send requests just below and above the limit and check that extra requests get 429 Too Many Requests with a Retry-After header. Verify the counter resets after the window and that limits apply per key or per IP as designed. Check that one user hitting the limit does not block others, and that normal traffic is not throttled.

What is the difference between statement coverage and branch coverage?

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Statement coverage measures the percentage of code statements executed by tests. Branch coverage measures whether every decision outcome, true and false, has been executed. Branch coverage is stronger: for 'if (amount > 1000) applyDiscount()', one test with 1500 gives 100 percent statement coverage, but you need a second test with 500 to cover the false branch. 100 percent branch coverage implies 100 percent statement coverage, not the other way round.

A developer changed a shared header component used on every page. What testing do you plan?

Testing TypesMedium

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Retest the change itself, then run a focused regression on every page type that uses the header: home, listing, detail, checkout and account. Check navigation links, search, login and logout state, cart count and the mobile menu. Do cross-browser and responsive checks because layout changes affect all sizes. A quick visual comparison against the previous build helps spot alignment issues across many pages.

What are the main testing differences between Android and iOS?

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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.

How do you review test cases?

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Peer review for clarity, coverage of requirements, correct expected results, test data and traceability, then update and baseline them.

How do you handle a bug found late in a release cycle?

Bug Life Cycle and JiraMedium

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Assess impact and risk, discuss with product and dev, decide to fix, defer with a workaround or delay release, and document the decision.

During a load test, some booking requests fail with a 'deadlock detected' error. What is happening and how do you report it?

Database TestingHard

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A deadlock happens when two transactions each hold a lock the other needs, so neither can continue. The database detects it and kills one transaction with an error. During testing it usually appears under concurrent load, for example two users booking the last seats at once, as random failures or 'deadlock detected' entries in logs. Testers report the exact actions and timing, and developers fix it with consistent lock order or shorter transactions.

What is a traceability matrix?

STLC and Test PlanningMedium

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A grid mapping requirements to test cases and defects, proving every requirement is tested.

What is configuration testing?

Testing TypesMedium

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Verifying the application works across different hardware, software and settings combinations.

What is API testing and why is it important?

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Testing services directly without the UI, checking status codes, responses, security and performance. It finds issues early and is faster than UI tests.

What is mobile app testing and what extra checks does it need?

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

What is interrupt testing in mobile apps?

Mobile TestingEasy

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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.

Tell me about a device-specific bug you found and how you reported it.

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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.

A user updates their phone number in the app, but the old number still appears in reports. What do you check?

Database TestingMedium

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First query the main users table to see whether the update was saved. If it was, check where the report reads from: a view, a reporting copy, a cache or a nightly ETL table. The report may simply be stale until the next refresh, which may be by design. If the main table still has the old value, check the API request, the update query and any errors in logs, then log a bug with both query results.

A report shows duplicate rows after a new release. How do you investigate in the database?

Database TestingMedium

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Run the report query with GROUP BY on the business key and HAVING COUNT(*) > 1 to find which records repeat. Then check whether the duplicates exist in the base table or are created by the query, usually a new join to a one-to-many table such as addresses. Compare the query before and after the release. Include the duplicate keys, the count and the suspected join in the bug report.

What is data-driven testing?

Automation Basics for Manual TestersMedium

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Data-driven testing runs the same test steps many times with different input and expected values taken from a table, CSV, JSON or spreadsheet. For example, one login test can run with valid users, locked users, wrong passwords and blank fields. It reuses the logic, makes adding cases easy and maps well to equivalence partitioning and boundary values from manual design. Tools support it through parameterised tests, such as pytest.mark.parametrize.

Write test cases for a one-to-one chat feature.

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Send and receive text messages and check order and timestamps. Test sent, delivered and read status. Send emojis, long messages, links and attachments within and over the size limit. Check messages sent while offline are queued and delivered on reconnect. Verify blocking a user stops messages. Test notifications when the app is in background. Check chat history after reinstall or on a second device, and that deleted messages disappear for both users if supported.

A user fills a long form, switches to another app and comes back. What should you test?

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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.

How do you test API error handling for invalid input?

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Send requests with missing required fields, wrong data types, values beyond limits, invalid formats such as a bad email, unknown fields and an empty or malformed JSON body. The API should return a 4xx code such as 400 or 422, a clear error message that names the field, and no stack trace or database details. Also check that nothing was partly saved in the database after the failed request.

What is the difference between smoke testing in CI and full regression?

Testing TypesMedium

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Smoke tests run on every build for quick feedback; full regression runs less often, such as nightly or before release.

A dashboard shows pass or fail status only with red and green dots. What is the issue?

Accessibility & Usability TestingEasy

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This relies on colour alone to give information, which fails WCAG criterion 1.4.1. Users with red-green colour blindness, which affects a noticeable share of men, cannot tell the states apart, and screen readers announce nothing. Recommend adding text or icons such as a tick and a cross with labels like 'Passed' and 'Failed', and accessible names for the dots. Test with a colour blindness simulator in browser developer tools.

A requirement says the page should load fast. How do you turn it into a test case?

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The word fast is not testable, so ask the product owner for a measurable target, for example the page loads within 3 seconds on a 4G network for 95 percent of requests. Agree on the conditions: device, network, data size and whether it is first load or cached. Then write the test with those conditions and expected time. Record the agreed number in the story so the expected result is not open to opinion.

What is the difference between a known issue and an open bug at release time?

Bug Life Cycle and JiraMedium

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An open bug is any defect not yet resolved. A known issue is an open bug that the team has consciously agreed to release with, after assessing its impact, and has documented in release notes or support notes, often with a workaround. Every known issue is an open bug, but not every open bug should ship. QA makes sure known issues are listed and approved by the product owner.

A feature passed all your test cases, but users say it is confusing. What went wrong?

Manual Testing BasicsMedium

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The tests verified the specification but did not validate the user experience. The test cases probably checked only functional outcomes and missed usability: unclear labels, too many steps or poor error messages. Next time, add usability heuristics to reviews, do exploratory sessions as a real user persona and involve users in UAT or demos. Log the current feedback as improvement items with clear examples.

What are SQL constraints?

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Rules such as NOT NULL, UNIQUE, PRIMARY KEY, FOREIGN KEY and CHECK that keep data valid and consistent.

How do you test a mobile app when the device storage is almost full?

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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.

How can you do basic performance checks with browser developer tools?

Performance and Security BasicsEasy

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Open developer tools and use the network tab with cache disabled to see each request's size and time, and the total load time. Look for very large images or scripts, slow API calls and requests that fail or repeat. Use throttling to simulate slow 3G or 4G. Run the built-in performance audit tool to get scores for load speed and suggestions. Record the numbers so you can compare with later builds.

Write a SQL query to find duplicate records.

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SELECT email, COUNT(*) FROM users GROUP BY email HAVING COUNT(*) > 1;

How do you test zoom, text resizing and reflow?

Accessibility & Usability TestingMedium

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Set browser zoom to 200 percent and check that all text is readable and no content or buttons are cut off. Then zoom to 400 percent, or use a 1280 pixel wide window, which gives a 320 CSS pixel viewport; content should reflow into one column without horizontal scrolling, except for things like data tables and maps. Also increase text spacing and the operating system font size to check that labels do not overlap.

What is the difference between a walkthrough and an inspection?

Manual Testing BasicsMedium

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Both are static review techniques. A walkthrough is informal and led by the author, who explains the document or code to peers to share knowledge and gather feedback. An inspection is the most formal review: it has defined roles such as moderator, reader and scribe, uses checklists, needs preparation and records defects and metrics. Inspections find more defects but take more effort.

Tell me about a time you found an important bug that others missed.

Manual Testing BasicsMedium

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Model answer: Situation: before a release of an insurance app, all regression tests had passed. Task: I was doing a final exploratory round. Action: I renewed a policy on the last day of the month and saw that the premium was calculated for 31 days in a 30-day month. I logged it with exact data and the formula difference. Result: the date logic was fixed before release, and I added month-end cases to the suite.

What goes into a test plan?

STLC and Test PlanningMedium

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Scope (in and out), objectives, approach, environments, schedule, roles, entry/exit criteria, risks and mitigation, deliverables and tools.

Notifications arrive late, and some screens look broken, only on certain Android phone brands. Why can this happen and what do you test?

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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.

What is localisation and internationalisation testing?

Testing TypesMedium

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Internationalisation tests that the product can support many languages and formats; localisation tests that a specific locale is correct for text, currency, date and layout.

Tell me about a time you used a test design technique to reduce the number of test cases.

Test Case DesignEasy

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Model answer: Situation: in my training project, a registration form had age, state and course fields, and my first draft had over 60 test cases. Task: cut effort without losing coverage. Action: I applied equivalence partitioning and boundary values to age and pairwise combinations for state and course. Result: I covered the same rules with 18 cases, my mentor approved them, and execution finished in half the time.

How do you convert existing manual test cases into automated scripts?

Automation Basics for Manual TestersMedium

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Pick a small set of stable, high-value regression cases first. Review each one: make steps precise, remove judgement-based checks and define clear expected results. Prepare test data that the script can create and clean up. Build reusable page objects and helpers for common steps like login. Automate, run several times to confirm stability, then link each script to its manual case ID and mark the manual case as automated.

What is TDD vs BDD?