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Bloomberg Automation Testing Interview Questions & Answers

Curated interview practice questions with answers. These are practice scenarios, not a verified list of past interview questions.

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01

What is the use of the this and super keywords?

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this refers to the current object; super refers to the parent class, used to call parent constructors and methods.
02

What new features came with Selenium 4?

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Relative locators, improved Grid, W3C compliance, new window or tab creation, Chrome DevTools Protocol access and element-level screenshots.
03

How do you test an API that depends on another service that is down?

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Use mocks or stubs such as WireMock to simulate the dependency and test your service in isolation.
04

Tests pass locally but fail on Jenkins. Why?

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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.
05

What is WebDriver and how does it communicate with the browser?

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WebDriver sends commands over HTTP (W3C protocol) to a browser-specific driver such as chromedriver, which controls the actual browser.
06

What are the advantages of version control for test code?

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Git tracks changes, enables code review, branching and rollback and lets teams collaborate on the framework safely.
07

How do you handle StaleElementReferenceException?

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Re-locate the element after the DOM refreshes, use explicit waits for the refreshed element, don't keep element references for long, or wrap the action in retry logic.
08

How does HashMap work internally?

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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.
09

What are listeners in TestNG?

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Classes like ITestListener that react to events such as test start, success or failure, commonly used for screenshots and reporting.
10

How do you handle iframes?

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switchTo().frame(index, name or element) enters the frame, and switchTo().defaultContent() returns to the main page.
11

What is JSON and how is it used in API testing?

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A lightweight text format of key-value pairs and arrays used in API requests and responses, validated field by field in tests.
12

How do you handle a web table in Selenium?

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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.
13

How do you handle multiple windows?

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String parent = driver.getWindowHandle(); for (String h : driver.getWindowHandles()) if (!h.equals(parent)) driver.switchTo().window(h); // ...then switch back to parent
14

What locators does Selenium support?

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id, name, className, tagName, linkText, partialLinkText, CSS selector and XPath. Prefer stable ids or CSS, using XPath when needed.
15

How do you verify response time and headers in REST Assured?

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Use then().time(lessThan(2000L)) and then().header("Content-Type", containsString("json")) along with body assertions.
16

What is method overriding and where is it useful in frameworks?

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A subclass redefines a parent method. Frameworks use it to customise base behaviour, such as overriding a wait or click method in a base page class.
17

What is Postman and how do you automate with it?

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An API client. Add tests in JavaScript, use environments and collections, and run them with Newman in a CI pipeline.
18

findElement vs findElements?

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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.
19

What is TestNG and why is it used with Selenium?

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A test framework offering annotations, grouping, prioritisation, parallel runs, data providers and reports, which structure and scale Selenium tests.
20

What is the difference between Comparable and Comparator in Java?

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Comparable defines the natural order inside the class (compareTo); Comparator defines custom orders externally (compare), useful for sorting test data in several ways.
21

How do you make WebDriver thread-safe for parallel runs?

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Store each driver in a ThreadLocal so every thread gets its own instance and tests do not interfere.
22

What are wrapper classes in Java?

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Classes such as Integer and Double that wrap primitive types as objects, needed for collections and for parsing text from web elements.
23

How do you calculate automation ROI?

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Compare effort saved by running automated tests repeatedly against the cost of building and maintaining scripts, counting execution time, defects found earlier and release speed.
24

Explain your CI/CD pipeline for tests.

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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.
25

How do you scroll a page in Selenium?

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Use JavascriptExecutor with window.scrollTo or scrollIntoView, or the Actions class scroll methods in Selenium 4.
26

How do you group tests?

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Tag tests with groups = {"smoke","regression"} and include or exclude them in testng.xml to run chosen sets.
27

Write an XPath for a button with the text "Login".

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//button[normalize-space()='Login'] //button[contains(text(),'Login')]
28

What is polymorphism and how does it show up in Selenium?

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One interface, many forms. WebDriver driver = new ChromeDriver() lets the same test code run on any browser class that implements WebDriver.
29

What is the difference between an array and an ArrayList?

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Arrays have a fixed size and can hold primitives; ArrayList grows dynamically, holds objects and offers helper methods.
30

What are the main OOP concepts in Java?

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Encapsulation, inheritance, polymorphism and abstraction. Testers use them to build reusable page classes, base tests and utility libraries.
31

What is an API and what are common HTTP methods?

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An interface for systems to talk to each other. GET reads, POST creates, PUT replaces, PATCH updates partially and DELETE removes.
32

POST vs PUT vs PATCH?

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POST creates a resource, PUT replaces the whole resource (idempotent) and PATCH updates part of it.
33

What is the difference between SOAP and REST?

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SOAP is a strict XML protocol with WSDL and WS-Security; REST is a lighter architectural style using HTTP and usually JSON.
34

What is contract testing?

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Verifying that a provider and consumer agree on request and response formats, using tools like Pact, to catch breaking changes early.
35

How do you handle a test that is flaky only in headless mode?

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Set window size explicitly, use proper waits, check animations and viewport differences, and capture screenshots and logs to find timing issues.
36

What are relative locators in Selenium 4?

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Locators such as above, below, toLeftOf and near that find elements by their position relative to another element.
37

What is Docker and how does it help tests?

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Docker packages tools in containers so tests run identically everywhere; Selenium Grid and browsers can be started quickly in containers.
38

Which reporting tools do you use?

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TestNG reports, ExtentReports and Allure give charts, screenshots and logs that are easy to share with the team.
39

What is the difference between @BeforeTest and @BeforeMethod?

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@BeforeTest runs once before all methods in a test tag of testng.xml; @BeforeMethod runs before every test method.
40

How do you validate a JSON response in REST Assured?

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Use then().statusCode(200).body("data.id", equalTo(5)), or extract() the response and assert fields with JsonPath.
41

What is a constructor and can it be overloaded?

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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.
42

What is the difference between static and non-static members?

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Static members belong to the class and are shared by all instances; non-static members belong to each object.
43

Difference between absolute and relative XPath?

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Absolute starts from the root (/html/...) and breaks easily; relative starts anywhere with // and is more stable, for example //input[@id='email'].
44

How would you automate a login flow with multiple user roles?

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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.
45

What is BDD and how does Cucumber work?

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Behaviour-driven development writes scenarios in Given-When-Then Gherkin that map to step definitions in code, so business and QA share one language.
46

How do you reduce flakiness in a CI pipeline?

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Stabilise waits and data, isolate tests, use retries cautiously, quarantine unstable tests, run in consistent containers and track flaky rates.
47

How do you run JavaScript in Selenium?

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Cast the driver to JavascriptExecutor and use executeScript, for example to scroll into view or click hidden elements.
48

Write a GET test in REST Assured.

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given().baseUri(url) .when().get("/users/1") .then().statusCode(200).body("id", equalTo(1));
49

What are the different types of waits in Selenium?

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Implicit, explicit (WebDriverWait with ExpectedConditions) and fluent waits; avoid mixing implicit and explicit waits and never rely on Thread.sleep.
50

How do you upload a file with Selenium?

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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.
51

Implicit vs explicit vs fluent wait?

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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.
52

How do you pass parameters from testng.xml?

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Define parameter name and value in the XML and read them with @Parameters in the test or configuration method.
53

String vs StringBuilder?

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String is immutable — every change creates a new object. StringBuilder is mutable and faster for repeated changes (not thread-safe; StringBuffer is).
54

What do HTTP status codes 200, 201, 400, 401, 403, 404 and 500 mean?

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200 OK, 201 Created, 400 bad request, 401 unauthenticated, 403 forbidden, 404 not found and 500 server error.
55

What is Selenium Grid and why use it?

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It runs tests in parallel across multiple machines and browsers using a hub and nodes, cutting execution time and increasing browser coverage.
56

How would you design an automation framework from scratch?

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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.
57

How do you retry failed tests in TestNG?

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Implement IRetryAnalyzer with a retry count and attach it through the test annotation or a listener to rerun flaky tests.
58

What are Java collections and which ones do testers use most?

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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.
59

What are exceptions and how do you handle them?

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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.
60

Difference between an abstract class and an interface?

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An abstract class can hold state and concrete methods; an interface defines a contract (with default methods since Java 8). A class extends one abstract class but can implement many interfaces.
61

How do you take a screenshot on failure in TestNG?

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Implement ITestListener.onTestFailure(): File src = ((TakesScreenshot) driver).getScreenshotAs(OutputType.FILE); then copy it into the reports folder.
62

What is the Page Object Model?

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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.
63

What is the execution order of TestNG annotations?

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@BeforeSuite → @BeforeTest → @BeforeClass → @BeforeMethod → @Test → @AfterMethod → @AfterClass → @AfterTest → @AfterSuite.
64

What are access modifiers in Java?

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public (everywhere), protected (package and subclasses), default (package) and private (same class), used to control visibility of test utilities.
65

What are try-with-resources and why use them?

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A try block that automatically closes resources such as file readers or streams, preventing leaks without a finally block.
66

Reverse a string in Java.

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String r = new StringBuilder(s).reverse().toString(); // or loop from the last index and append each character
67

What is the Hybrid framework?

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A framework combining data-driven, keyword-driven and POM approaches with reporting and utilities, giving flexibility and reuse.
68

What is REST Assured?

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A Java library that makes API tests readable using given-when-then, with easy request building, response validation and JSON path support.
69

How would you design a CI pipeline for nightly regression?

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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.
70

How do you switch between windows and tabs?

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Get getWindowHandles(), loop to find the target, and call driver.switchTo().window(handle); switch back using the stored parent handle.
71

List common TestNG annotations and their order.

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BeforeSuite, BeforeTest, BeforeClass, BeforeMethod, Test, AfterMethod, AfterClass, AfterTest and AfterSuite.
72

What is a DataProvider in TestNG?

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@DataProvider returns Object[][]; a @Test(dataProvider = "name") method runs once per row — the basis of data-driven tests, often reading Excel or JSON.
73

Difference between final, finally and finalize?

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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.
74

What is OAuth 2.0 in API testing?

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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.
75

What is Selenium and what are its components?

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An open-source suite for browser automation: WebDriver, IDE, Grid and the older RC. WebDriver controls browsers through their native drivers.
76

What is data-driven testing?

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Running the same test logic with multiple data sets from Excel, CSV, JSON or a database, so coverage increases without duplicating code.
77

How do you decide what to automate?

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Automate stable, repetitive, high-risk and data-heavy flows (smoke, regression). Skip one-time tests, frequently changing UI and checks needing human judgement. Compare run frequency × manual time with build and maintenance cost.
78

What is a Jenkins pipeline?

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A scripted or declarative Jenkinsfile that defines stages such as build, test and deploy as code stored with the project.