D. E. Shaw Automation Testing Interview Questions & Answers

BeforeSuite, BeforeTest, BeforeClass, BeforeMethod, Test, AfterMethod, AfterClass, AfterTest and AfterSuite.

Stabilise waits and data, isolate tests, use retries cautiously, quarantine unstable tests, run in consistent containers and track flaky rates.

ArrayList and LinkedList for lists, HashSet for unique values, HashMap for key-value test data, and Iterator for traversing them, for example collecting web elements in a list.

One interface, many forms. WebDriver driver = new ChromeDriver() lets the same test code run on any browser class that implements WebDriver.

Implement ITestListener.onTestFailure(): File src = ((TakesScreenshot) driver).getScreenshotAs(OutputType.FILE); then copy it into the reports folder.

final makes a variable, method or class unchangeable; finally is a block that always runs after try-catch; finalize is a deprecated method called before garbage collection.

A special method that initialises an object. It can be overloaded with different parameters, and testers use it to pass the WebDriver into page classes.

Do not automate it; ask for a test environment where CAPTCHA is disabled or use test keys, or a bypass token agreed with developers.

Runtime events that disrupt flow. Use try-catch-finally, throw, throws, and custom exceptions; checked exceptions must be handled while unchecked ones need not be.

id, name, className, tagName, linkText, partialLinkText, CSS selector and XPath. Prefer stable ids or CSS, using XPath when needed.

A Java library that makes API tests readable using given-when-then, with easy request building, response validation and JSON path support.

Use mocks or stubs such as WireMock to simulate the dependency and test your service in isolation.

Use external files or APIs and database setup scripts, generate unique data per run, and clean up afterwards so tests stay independent.

Create a job or pipeline that checks out code, runs mvn test, publishes reports and triggers on commits or schedules.

Absolute starts from the root (/html/...) and breaks easily; relative starts anywhere with // and is more stable, for example //input[@id='email'].

Use Apache POI for Excel and the Properties class for config files, loaded in a utility class so tests read data instead of hard-coding it.

Headless mode or screen resolution, timing issues, environment data, missing dependencies, browser–driver version mismatch or parallel conflicts. Check logs and failure screenshots and make waits robust.

Lambdas are short anonymous functions; streams process collections declaratively with filter, map and collect, for example filtering link text from a list of elements.

An open-source suite for browser automation: WebDriver, IDE, Grid and the older RC. WebDriver controls browsers through their native drivers.

If the element is <input type="file">, use element.sendKeys("C:/path/file.pdf"). Use the Robot class or AutoIt only as a last resort for OS dialogs.

ArrayList has fast random access and slower inserts in the middle; LinkedList has fast inserts and deletes but slow access by index.

Locate rows and columns with XPath such as //table//tr and //td, loop through them to read or click cells, or build the XPath dynamically from the row text.

Get getWindowHandles(), loop to find the target, and call driver.switchTo().window(handle); switch back using the stored parent handle.

Code pushed to Git → Jenkins job triggers (webhook or schedule) → mvn clean test with the suite XML → reports and screenshots published → notifications on Slack/email → failures triaged before release.

Comparable defines the natural order inside the class (compareTo); Comparator defines custom orders externally (compare), useful for sorting test data in several ways.

Mouse and keyboard actions such as hover, drag and drop, double click, right click and key combinations, built with moveToElement(...).perform().

Use TestNG parallel="methods | classes | tests" with thread-count, keep WebDriver in a ThreadLocal, and use Selenium Grid or a cloud grid for multiple browsers.

driver.switchTo().alert() lets you accept, dismiss, read text or send keys. Browser windows are handled with window handles.

Running the same test logic with multiple data sets from Excel, CSV, JSON or a database, so coverage increases without duplicating code.

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.

Maven project → POM with a BasePage → driver factory with ThreadLocal → config files → data-driven utilities (Excel/JSON) → TestNG or Cucumber runner → logging → Extent reports with screenshots on failure → Jenkins pipeline.

findElement returns the first match and throws NoSuchElementException if nothing is found. findElements returns a List (empty if nothing is found) — handy to check whether an element exists.

A try block that automatically closes resources such as file readers or streams, preventing leaks without a finally block.

Tag tests with groups = {"smoke","regression"} and include or exclude them in testng.xml to run chosen sets.

Implicit wait applies globally to element lookups. Explicit wait waits for a specific condition (WebDriverWait + ExpectedConditions). Fluent wait is an explicit wait with custom polling and ignored exceptions.

Continuous Integration builds and tests every commit, and Continuous Delivery ships automatically. Automated tests give fast feedback and gate releases.

A method annotated with @DataProvider returns a 2D object array and the test with dataProvider = "name" runs once per row.

Keep credentials in external data, parameterise the test with a data provider, reuse a login method in a page class, and clear sessions between roles.

Hard assert stops the test at the first failure; SoftAssert collects failures and reports them together when assertAll() is called.

A design pattern where each page is a class holding its locators and actions, so tests stay readable and a locator change is fixed in one place.

It uses the key's hashCode to find a bucket and equals to resolve collisions, giving O(1) average lookups; Java 8 converts long buckets into trees.

It runs tests in parallel across multiple machines and browsers using a hub and nodes, cutting execution time and increasing browser coverage.

Overloading: same method name, different parameters, in the same class (compile time). Overriding: a subclass redefines a parent method with the same signature (runtime polymorphism). WebDriver driver = new ChromeDriver() is runtime polymorphism.

Docker packages tools in containers so tests run identically everywhere; Selenium Grid and browsers can be started quickly in containers.

ArrayList stores an ordered list (e.g. all product names on a page). HashMap stores key–value pairs (e.g. test data or config properties).

Use headers such as Bearer tokens, basic auth, API keys or OAuth flows; fetch a token in a setup step and reuse it.

A helper that initialises @FindBy elements lazily using initElements; some teams skip it in favour of plain By locators.

Define parameter name and value in the XML and read them with @Parameters in the test or configuration method.

Static members belong to the class and are shared by all instances; non-static members belong to each object.

Classes such as Integer and Double that wrap primitive types as objects, needed for collections and for parsing text from web elements.

close() closes the current window; quit() closes all windows and ends the driver session.

200 OK, 201 Created, 400 bad request, 401 unauthenticated, 403 forbidden, 404 not found and 500 server error.

Verifying that a provider and consumer agree on request and response formats, using tools like Pact, to catch breaking changes early.

Implement IRetryAnalyzer with a retry count and attach it through the test annotation or a listener to rerun flaky tests.

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.

@BeforeTest runs once before all methods in a test tag of testng.xml; @BeforeMethod runs before every test method.

Arrays have a fixed size and can hold primitives; ArrayList grows dynamically, holds objects and offers helper methods.

Git tracks changes, enables code review, branching and rollback and lets teams collaborate on the framework safely.

Implicit, explicit (WebDriverWait with ExpectedConditions) and fluent waits; avoid mixing implicit and explicit waits and never rely on Thread.sleep.

Set window size explicitly, use proper waits, check animations and viewport differences, and capture screenshots and logs to find timing issues.

A test framework offering annotations, grouping, prioritisation, parallel runs, data providers and reports, which structure and scale Selenium tests.

Store each driver in a ThreadLocal so every thread gets its own instance and tests do not interfere.

An interface for systems to talk to each other. GET reads, POST creates, PUT replaces, PATCH updates partially and DELETE removes.

Locators such as above, below, toLeftOf and near that find elements by their position relative to another element.

TestNG reports, ExtentReports and Allure give charts, screenshots and logs that are easy to share with the team.

String is immutable — every change creates a new object. StringBuilder is mutable and faster for repeated changes (not thread-safe; StringBuffer is).