Curated interview practice questions with answers. These are practice scenarios, not a verified list of past interview questions.
About ZS Associates hiring for Automation Testing roles
ZS is a management consulting and technology firm known for its work with pharmaceutical and life sciences companies on sales, marketing and analytics. Its India offices in Pune, Gurugram and Bengaluru handle analytics, data engineering and technology delivery. It hires for business analysts, decision analytics associates, data engineers and data scientists.
For Automation Testing roles, this ZS Associates practice set focuses most on TestNG Framework (8), Core Java for Testers (6), Selenium Grid & Docker (5), API Testing and CI/CD (4). It has 8 easy, 28 medium, 4 hard questions, so you can start easy and work up to the harder ones.
Company type
Consulting
Headquarters
Evanston, Illinois, USA
Main India offices
Pune, Gurugram, Bengaluru
ZS Associates Automation Testing interview process
Online assessment (aptitude + analytics)
Case interview
Technical interview
Managerial round
HR round
Typical pattern based on public candidate experiences. Rounds vary by role, team and year.
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01
How do you handle authentication types in REST Assured?
Basic auth uses auth().preemptive().basic(user, pass). Bearer tokens are set as a header: header("Authorization", "Bearer " + token). OAuth 2.0 can use auth().oauth2(token) after fetching the token from the token endpoint. API keys go in a header or query param. Fetch tokens once per suite or cache them with an expiry check rather than logging in before every test.
02
Half of your TestNG tests are skipped in CI with no failure shown. What could cause it?
Usually a configuration method failed, such as @BeforeClass or @BeforeSuite throwing an exception, which makes TestNG skip dependent tests. Other causes are dependsOnMethods on a failed test, a group filter excluding setup methods without alwaysRun, or a DataProvider that threw an exception. Check the configuration failures section of the report and the log for the first exception.
03
What is the Optional class in Java and where is it useful in test code?
Optional is a container that may or may not hold a value, introduced in Java 8 to avoid returning null. In test code it suits lookups that can legitimately find nothing, such as finding a row in a table or reading an optional config key. Callers use orElse, orElseThrow or ifPresent instead of null checks. For example, findRowByName(name).orElseThrow(() -> new AssertionError(name + " not found")) gives a clear failure message.
An authorisation framework where a client obtains an access token from an auth server and sends it as a Bearer token; tests fetch and reuse the token in setup.
05
How do you handle a component that appears inside many different pages, like a modal dialog?
Create a ModalComponent class scoped to the modal root element, with methods like title(), confirm() and cancel(). Pages that open modals return the component, such as cartPage.removeItem() returning ConfirmModal. The component waits for itself to appear and disappear. This keeps modal logic in one place and avoids copying locators into every page.
06
Tests running inside Docker cannot reach the application running on the host's localhost. Why, and how do you fix it?
Inside a container, localhost means the container itself, not the host machine. On Docker Desktop use host.docker.internal as the host name. On Linux add extra_hosts with host.docker.internal:host-gateway, or use the host's IP. A cleaner option is running the application in the same Compose network and calling it by its service name, such as http://web:8080. Make sure the app listens on 0.0.0.0, not only 127.0.0.1.
07
Tell me about a time a flaky test cost your team time and how you fixed it permanently.
Situation: a checkout test failed about one run in five and the team started ignoring red builds. Task: fix the root cause, not just rerun it. Action: I added logs and screenshots, found it raced with an async price recalculation, replaced a fixed sleep with a wait on the updated total and asked developers for a loading flag. Result: zero failures in the next sixty runs, and the team trusted red builds again.
A quality gate is a rule a build must pass before moving forward, such as all smoke tests passing, code coverage above a threshold, no critical static analysis issues, or no new high-severity vulnerabilities. If the gate fails, the pipeline stops and the change is not deployed. Gates make quality an automatic decision instead of a manual check.
09
A test configuration value has to be the same for the whole run and accessed from many classes. How do you implement it?
Create a ConfigReader that loads properties once, using a singleton or a static holder initialised lazily in a thread-safe way, and exposes typed getters like getInt("timeout"). Let system properties and environment variables override file values so CI can change them. Keep it read-only after loading so parallel threads cannot change settings mid-run.
10
What is the execution order of TestNG annotations?
Pre-processors run before a sampler, for example a JSR223 PreProcessor that builds a signature or timestamp, or User Parameters that set values per thread. Post-processors run after a sampler and usually extract data from the response, such as JSON Extractor, Regular Expression Extractor or Boundary Extractor, storing it as a variable for later requests. Their scope depends on where they sit in the tree, so place them as children of the right sampler.
13
How do you verify that an element is displayed, enabled or selected?
Serialization converts a Java object (POJO) into JSON for the request body; deserialization converts the response JSON back into a Java object. REST Assured does this automatically when Jackson or Gson is on the classpath: body(userPojo) serializes and response.as(User.class) deserializes. Using POJOs gives type safety, IDE support and cleaner assertions compared with hand-written JSON strings.
15
What are generics in Java and how do they help in a test framework?
Generics let classes and methods work with a type parameter while keeping compile-time type safety, such as List<String> or a method <T> T readJson(String path, Class<T> type). In a framework they let you write one reusable helper for many types, for example a generic API client that deserializes responses into any POJO, or a BasePage method that returns the correct page type for chaining. They remove casts and catch type errors at compile time.
16
A runtime permission pop-up appears on first launch and breaks your Android tests. How do you handle it?
The cleanest fix is the capability appium:autoGrantPermissions set to true, which grants all permissions the app declares at install time. If you need to test the permission flow itself, handle the dialog explicitly by waiting for the Allow button using its resource-id and clicking it. Another option is granting a specific permission with adb shell pm grant before the test. Avoid blind try-catch around taps, because it hides real failures.
17
How do you handle a test that is flaky only in headless mode?
dryRun=true makes Cucumber parse all feature files and check every step has a matching definition without actually executing anything. It is fast and is useful after writing new features, during refactoring, or as a quick CI gate to catch undefined or ambiguous steps. It also prints snippets for missing step definitions that you can paste and implement.
@Factory creates test class instances dynamically, each with different constructor data, so all tests in the class run once per instance. For example a factory can create LoginTests for chrome and firefox. It differs from DataProvider, which runs one method many times with different arguments. Factory is useful when a whole class should repeat for each configuration.
20
What is API testing and why is it done before UI testing?
API testing checks the business logic layer directly by sending requests and validating responses, status codes, data and errors. It is faster, more stable and cheaper to maintain than UI tests, and it can start as soon as endpoints exist, before the UI is ready. Most functional rules should be covered at API level, leaving UI tests for key user journeys.
Generally no. Page objects should expose state and actions, such as getErrorMessage() or isLoggedIn(), and tests should make the assertions. This keeps page classes reusable across positive and negative tests and keeps the test intent visible. A small exception is a simple check that the correct page has loaded, often done in the constructor or an isAt() method.
23
What is the New Session Queue in Selenium Grid 4 and what happens when all slots are busy?
When a test requests a session and no node slot matches, the request waits in the New Session Queue instead of failing immediately. The distributor picks it up when a matching slot frees. If it waits longer than the session request timeout, which is 300 seconds by default, the client gets a SessionNotCreatedException. Tuning this timeout and matching thread count to slot count prevents long waits and timeouts in CI.
24
You configured 50 parallel threads but only 8 tests run at a time on the Grid. Why?
The Grid only has 8 free slots, so the other requests wait in the New Session Queue. Total parallelism equals nodes multiplied by max sessions per node, not the TestNG thread count. Check the Grid UI for slot count. To run more, scale the node containers, raise max sessions if hardware allows, or use a larger grid. Otherwise reduce threads to match slots so waiting requests do not time out.
25
A login action can lead either to the dashboard or to an error message. How should the page object method return?
Make the outcome explicit with separate methods instead of one method guessing. For example loginAs(user) returns DashboardPage for valid credentials, while loginExpectingError(user) returns the same LoginPage so the test can check the error. Each method waits for its expected page and fails clearly if it does not appear. This keeps tests readable and avoids returning a generic Object or checking types in tests.
compile is the default and available everywhere. test is only for test compile and run, such as TestNG and REST Assured. provided is needed for compiling but supplied at runtime by the container. runtime is not needed to compile but needed to run, like JDBC drivers. system and import are rarer. In test projects, mark test libraries as test scope unless framework code in src/main uses them.
29
What is RemoteWebDriver and how is it different from ChromeDriver?
ChromeDriver starts and controls a browser on the same machine as the test. RemoteWebDriver sends the same WebDriver commands over HTTP to a remote endpoint, such as a Selenium Grid, a Docker container or a cloud provider, which starts the browser elsewhere. You pass the Grid URL and browser options, and the rest of the test code stays the same. ChromeDriver itself actually extends RemoteWebDriver.
30
How do you get reports, screenshots and downloaded files out of a Docker container?
Use volumes. A bind mount maps a host folder into the container, for example -v $(pwd)/target:/app/target, so reports written in the container appear on the CI agent for archiving. Named volumes are managed by Docker and suit data that should survive restarts. For browser downloads, mount the node's download folder or enable the Grid's managed downloads with the se:downloadsEnabled capability to fetch files through the Grid API.
31
Write a DataProvider that supplies two sets of login data and a test that uses it.
Send invalid or missing fields, wrong data types, values beyond limits, invalid IDs, expired or missing tokens, wrong HTTP methods and malformed JSON. Assert the correct status (400, 401, 403, 404, 405, 422) and a clear error body without stack traces. Negative tests often find more defects than happy paths because validation and security checks are frequently incomplete.
Encapsulation: private locators with public page methods. Inheritance: pages extend a BasePage. Polymorphism: the WebDriver interface for different browsers. Abstraction: utility layers hiding Selenium details.
34
How do you handle an element inside a shadow DOM in Selenium 4?
Find the shadow host element, then call getShadowRoot() to get a SearchContext, and search inside it with CSS selectors: driver.findElement(By.cssSelector("my-app")).getShadowRoot().findElement(By.cssSelector("#submit")). XPath does not work inside shadow roots. For nested shadow roots, repeat the step for each host. Closed shadow roots cannot be accessed this way.
Run mvn dependency:tree to see which versions are pulled in transitively. Maven picks the nearest version, which may not be the one you need. Fix by declaring the required version in dependencyManagement, excluding the unwanted transitive dependency with exclusions, or upgrading the library that brings the old version. Conflicts often appear as NoSuchMethodError or ClassNotFoundException at runtime.
36
What is the difference between average, median and 95th percentile response time?
Average is the sum divided by count, so a few very slow requests can distort it. Median is the middle value, meaning half the requests were faster. The 95th percentile means 95 percent of requests were faster than that value, which reflects what most users experience including slow cases. SLAs are usually written on 90th, 95th or 99th percentiles because averages hide long tails that frustrate real users.
37
How do you extract an auth token with JSON Extractor and use it in later JMeter requests?
Add a JSON Extractor as a child of the login sampler. Set the variable name to token, the JSON path expression to $.access_token, match number 1 and a default like TOKEN_NOT_FOUND so failures are visible. Then add an HTTP Header Manager at Thread Group level with Authorization set to Bearer ${token}. Each thread extracts and uses its own token, because JMeter variables are per thread.
38
How would you design a CI pipeline for nightly regression?
Schedule the job, spin up environments or containers, run suites in parallel, store reports and screenshots, notify failures on Slack or email and track trends.
39
Your price comparison test fails because 19.99 + 0.01 is not equal to 20.0. Why?
double uses binary floating point, which cannot represent many decimal values exactly, so small rounding errors appear. For money, use BigDecimal created from strings and compare with compareTo(), or compare doubles with a tolerance such as Assert.assertEquals(actual, expected, 0.001). Also strip currency symbols and commas before parsing UI text.
40
What is the difference between parallel="methods", "classes" and "tests" in testng.xml?
methods runs each @Test method in its own thread, giving the most parallelism but requiring fully independent tests and thread-safe drivers. classes runs all methods of one class in the same thread, with different classes in parallel. tests runs each <test> tag in parallel, often used to run different browsers. instances is also available for factory instances. thread-count sets the pool size.
Tips to crack the ZS Associates Automation Testing interview
Learn pharma commercial basics like sales force effectiveness, market share and prescriber data for case questions.
Practise case interviews and guesstimates with a clear structure, as consulting rounds are central at ZS.
Revise Excel, SQL and basic statistics, since associate roles involve heavy data analysis.
Keep a one-minute story ready for every project on your CV: problem, your part, tools, result.
Practise the hard questions on this page aloud; ZS Associates interviewers usually ask follow-ups on your first answer.
Frequently asked questions
How many rounds are there in the ZS Associates Automation Testing interview?
Candidates usually go through 5 stages: Online assessment (aptitude + analytics); Case interview; Technical interview; Managerial round; HR round. The exact rounds change with the role, team, location and your experience, so confirm the process with the recruiter.
Which topics should I prepare for the ZS Associates Automation Testing interview?
This practice set leans on TestNG Framework (8), Core Java for Testers (6), Selenium Grid & Docker (5), API Testing and CI/CD (4). Revise those first, then practise explaining one or two of your own projects end to end, because most ZS Associates interviewers ask you to walk through real work.
Are these the exact questions asked at ZS Associates?
No. These are curated practice questions that match the skills and difficulty usually tested in consulting interviews like ZS Associates's. They are not a leaked or verified list of past questions.
Where does ZS Associates hire Automation Testing professionals in India?
ZS Associates has large teams in Pune, Gurugram, Bengaluru. Openings and locations change often, so check the ZS Associates careers page and filter by city and experience.
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