60+ Sdet Engineer Interview Questions and Answers

I have worked on multiple projects involving Selenium API for automated testing of web applications.

• Developed test scripts using Selenium WebDriver to automate testing of web applications

• Utilized Selenium Grid for parallel testing across different browsers and platforms

• Integrated Selenium with testing frameworks like TestNG or JUnit for test execution and reporting

• Implemented Page Object Model design pattern for better test maintenance and readability

Yes, the internal data structure can be changed without affecting user interaction as long as public methods remain the same.

• Use abstraction to hide implementation details from users

• Ensure public methods have consistent behavior regardless of internal data structure

• Consider using interfaces or abstract classes to define common behavior

Run time polymorphism is the ability of a method to do different things based on the object it is acting upon.

• Run time polymorphism is achieved through method overriding in object-oriented programming.

• It allows a subclass to provide a specific implementation of a method that is already provided by its superclass.

• The actual method that gets called is determined by the type of object at run time.

• Example: Animal class has a method 'makeSound'. Dog and Cat classes extend Animal a...read more

I have designed reusable methods for data validation, logging, and error handling.

• Created a data validation method that checks for required fields and data types

• Implemented a logging method that records important events and errors

• Developed an error handling method that gracefully handles exceptions and provides detailed error messages

Selenium program to automate adding items to cart on Swiggy

• Launch the Swiggy website using Selenium WebDriver

• Search for desired food items and add them to cart

• Verify items are added correctly before proceeding to checkout

I have implemented RESTful APIs using Node.js and Express framework in my project.

• Implemented CRUD operations for managing user data

• Used authentication middleware for secure access

• Integrated third-party APIs for external data retrieval

The API for capturing audio files is MediaRecorder in Android. Gradle is a build automation tool for Android projects.

• MediaRecorder API is used for capturing audio files in Android

• Gradle is a build automation tool used for building, testing, and deploying Android projects

• Example: MediaRecorder recorder = new MediaRecorder();

• Example: Gradle file for an Android project is typically named build.gradle

To center a div horizontally and vertically, use CSS with flexbox or grid layout

• Use CSS flexbox or grid layout to center the div both horizontally and vertically

• For flexbox, set display: flex; on the parent container and justify-content: center; align-items: center; on the child div

• For grid layout, set display: grid; on the parent container and place the child div in the center using grid-column and grid-row properties

Encapsulation is the concept of bundling data and methods that operate on the data into a single unit, while abstraction is the concept of hiding the implementation details and showing only the necessary features of an object.

• Encapsulation is about wrapping the data (variables) and methods (functions) that operate on the data into a single unit (class).

• Abstraction is about hiding the implementation details and showing only the necessary features of an object.

• Encapsulation hel...read more

Code to check if a string meets password requirements using built-in Java functions.

• Use String class methods like length(), contains(), matches() to check for password requirements.

• Use regular expressions to validate password requirements such as minimum length, uppercase, lowercase, digits, special characters.

• Example: String password = "Pass123!"; boolean isValid = password.length() >= 8 && password.matches(".*[A-Z].*") && password.matches(".*[a-z].*") && password.matches("....read more

Popular HTTP status codes and their meanings

• 200 - OK: Request succeeded

• 404 - Not Found: Resource not found

• 500 - Internal Server Error: Server error

• 401 - Unauthorized: Authentication required

• 302 - Found: Resource temporarily moved

• 503 - Service Unavailable: Server unavailable

To get all the links available on a page, you can use web scraping techniques.

• Use a web scraping tool like BeautifulSoup in Python or Selenium to extract all the links from the page

• Identify the HTML elements that contain the links, such as tags with href attributes

• Iterate through the elements to extract the URLs and store them in a list

Different methods to reverse strings in an array

• Use built-in functions like reverse() in JavaScript

• Iterate through each string and reverse characters manually

• Use recursion to reverse each string

Code for nested dictionary

• Use curly braces to define the outer dictionary

• Use square brackets to define the inner dictionaries

• Access values using keys

Printing all prime numbers from 1 to N.

• Iterate from 2 to N and check if each number is prime or not.

• Use a nested loop to check if a number is divisible by any number less than it.

• If a number is not divisible by any number less than it, it is a prime number.

• Print all prime numbers found.

A linked list is a linear data structure where each element is a separate object with a reference to the next element.

• Each element in a linked list is called a node

• Nodes are connected using pointers or references

• Linked lists can be singly linked (each node points to the next) or doubly linked (each node points to the next and previous)

Program to remove duplicate numbers from array of strings

• Iterate through the array and store each element in a set to keep track of unique elements

• If an element is already in the set, remove it from the array

• Return the array with duplicates removed

Waits in Selenium are used to make the automation script wait for a certain condition to be met before proceeding.

• There are three types of waits in Selenium: Implicit Wait, Explicit Wait, and Fluent Wait.

• Implicit Wait sets a default waiting time for the entire script to wait for an element to be found.

• Explicit Wait is used to wait for a certain condition to occur before proceeding to the next step.

• Fluent Wait is a more flexible wait that allows you to define the maximum amoun...read more

Backward compatibility refers to the ability of a system to accept input intended for an older version of the system.

• Allows newer versions of software to work with data or systems from older versions

• Ensures that changes in the software do not break compatibility with existing data or systems

• Helps in smooth transition and adoption of new versions without disrupting existing processes

Equivalence partitioning is a software testing technique where input data is divided into partitions and only one value from each partition is tested.

• Input data is divided into groups or partitions based on similar characteristics

• One value from each partition is selected as a representative for testing

• Helps in reducing the number of test cases while ensuring maximum coverage

• Example: Testing a login form with valid, invalid, and boundary input partitions

Linear gradient in CSS is a gradual transition between two or more colors along a straight line.

• Linear gradient is created using the linear-gradient() function in CSS.

• It allows for a smooth transition of colors from one point to another along a straight line.

• You can specify the direction, angle, and color stops for the gradient.

• Example: background: linear-gradient(to right, red, blue);

Use dynamic programming to find the longest strictly increasing path in a matrix.

• Use dynamic programming to keep track of the longest increasing path ending at each cell.

• Start from each cell and recursively explore all 4 directions to find the longest increasing path.

• Update the length of the longest increasing path at each cell based on the maximum length from its neighbors.

Implement LFU cache using OOPs concepts

• Create a class for LFU cache with methods like get, put, and remove

• Use a hashmap to store key-value pairs and a hashmap to store frequency of each key

• Implement a doubly linked list to store keys with the same frequency

PUT and PATCH are HTTP methods used for updating resources in RESTful APIs.

• PUT is used to update or replace an existing resource entirely

• PATCH is used to partially update an existing resource

• PUT is idempotent, meaning multiple identical requests will have the same effect as a single request

• PATCH is not idempotent, meaning multiple identical requests may have different effects

A paradox in testing refers to a situation where a test case both passes and fails at the same time.

• Paradox in testing can occur when a test case has conflicting requirements or conditions.

• It can also happen when there are errors in the test setup or execution that lead to unexpected results.

• For example, a test case may pass when run individually but fail when run as part of a test suite due to dependencies.

• Identifying and resolving paradoxes in testing is crucial for ensurin...read more

SQL joins are used to combine rows from two or more tables based on a related column between them.

• SQL joins are used to retrieve data from multiple tables based on a related column.

• Types of SQL joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.

• INNER JOIN returns rows when there is at least one match in both tables.

• LEFT JOIN returns all rows from the left table and the matched rows from the right table.

• RIGHT JOIN returns all rows from the right table and the match...read more

To handle dropdown in Selenium, use Select class from Selenium WebDriver API.

• Create a Select object by locating the dropdown element using findElement() method.

• Use selectByVisibleText(), selectByValue(), or selectByIndex() methods to select an option.

• To deselect an option, use deselectByVisibleText(), deselectByValue(), or deselectByIndex() methods.

Projects and queries involve understanding and working on various software projects and related inquiries.

• Projects involve developing, testing, and maintaining software applications.

• Queries may include troubleshooting issues, optimizing performance, and implementing new features.

• Examples of queries include debugging a software bug, improving code efficiency, and integrating a new API.

Stress testing in network involves simulating high traffic loads to evaluate performance and stability.

• Use tools like JMeter, LoadRunner, or Apache Bench to generate high traffic loads.

• Gradually increase the number of concurrent users or requests to find the breaking point.

• Monitor network performance metrics like latency, throughput, and error rates during the test.

• Identify bottlenecks or weak points in the network infrastructure and optimize accordingly.

• Repeat the test multi...read more

The 7 layers of the OSI model are: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

• Physical layer - deals with physical connections and signals

• Data Link layer - responsible for node-to-node communication

• Network layer - handles routing and forwarding

• Transport layer - ensures end-to-end communication

• Session layer - manages sessions between applications

• Presentation layer - translates data into a format that the application layer can understand

• Appl...read more

OOPS concepts are fundamental to object-oriented programming and include inheritance, encapsulation, polymorphism, and abstraction.

• Inheritance: Allows a class to inherit properties and behavior from another class. Example: class Dog extends Animal.

• Encapsulation: Bundling data and methods that operate on the data into a single unit. Example: private variables and public methods.

• Polymorphism: Ability to present the same interface for different data types. Example: method overlo...read more

Bubble sort using recursion is a sorting algorithm that repeatedly steps through the list, compares adjacent elements, and swaps them if they are in the wrong order.

• Define a recursive function that takes an array of strings as input

• Base case: if the array length is 1, return the array

• Recursive case: compare adjacent elements and swap if necessary, then recursively call the function with the updated array

• Repeat the process until the array is sorted

Dbms schema design for a blog app involves creating tables for users, posts, comments, and tags.

• Create a table for users with columns like user_id, username, email, password

• Create a table for posts with columns like post_id, title, content, user_id (foreign key)

• Create a table for comments with columns like comment_id, content, post_id (foreign key), user_id (foreign key)

• Create a table for tags with columns like tag_id, name

• Create a many-to-many relationship table between post...read more

Various methods to check if a string is a palindrome

• Reverse the string and compare with the original string

• Iterate through the string from both ends towards the middle

• Use a stack to push the characters of the string and then pop them to compare with the original string

Selenium is a popular open-source automation testing tool used for web applications.

• Selenium is used for automating web browsers.

• It supports multiple programming languages like Java, Python, C#, etc.

• Selenium WebDriver is the most commonly used component for writing automation scripts.

• Selenium Grid is used for parallel execution of test cases across different browsers and operating systems.

QA stress testing is a type of testing that evaluates the system's behavior under stressful conditions to ensure its stability and performance.

• QA stress testing involves putting the system under high load to identify its breaking point.

• It helps in determining how the system handles heavy traffic, peak loads, and resource exhaustion.

• The goal of QA stress testing is to uncover potential performance issues, bottlenecks, and weaknesses in the system.

• Examples of stress testing inc...read more

Selenium is a popular open-source tool used for automating web browsers for testing purposes.

• Selenium is used for automating web browsers to test web applications.

• It supports multiple programming languages like Java, C#, Python, etc.

• Selenium can simulate user interactions like clicking buttons, entering text, etc.

• It can run tests across different browsers and platforms.

• Selenium WebDriver is the most commonly used component for writing test scripts.

Program to find the longest unique string in an array of strings

• Iterate through each string in the array

• For each string, create a set to store unique characters

• Check each character in the string and add it to the set if it's not already present

• Keep track of the length of the current unique string and update the longest unique string found so far

• Return the longest unique string

SQL is a programming language used to manage and manipulate data in relational databases.

• SQL stands for Structured Query Language

• It is used to communicate with databases to perform tasks like querying, updating, and deleting data

• Common SQL commands include SELECT, INSERT, UPDATE, DELETE

• Examples of popular databases that use SQL include MySQL, PostgreSQL, Oracle

Code to reverse words in string

• Split the string into an array of words

• Reverse the array of words

• Join the reversed array back into a string

A clean and user-friendly navbar design for easy navigation on a website

• Include important links such as Home, About Us, Services, Contact

• Use clear and concise labels for each navigation item

• Consider using dropdown menus for subcategories

• Ensure the navbar is responsive for different screen sizes

This is a classic puzzle involving dividing 25 horses into groups of 5.

• Divide the 25 horses into 5 groups of 5 horses each.

• You can achieve this by using a weighing scale to compare groups of horses.

• The goal is to identify the fastest 3 horses among the 25.

HashMap is a data structure that stores key-value pairs and allows for fast retrieval of values based on keys.

• HashMap is part of the Java Collections framework.

• It uses hashing to store key-value pairs in an array.

• It allows for quick retrieval of values based on keys.

• HashMap does not maintain insertion order of elements.

• Example: HashMap map = new HashMap<>();

Different waits in Selenium include implicit wait, explicit wait, and fluent wait.

• Implicit wait: Waits for a certain amount of time before throwing a NoSuchElementException.

• Explicit wait: Waits for a certain condition to occur before proceeding further in the code.

• Fluent wait: Waits for a condition to be true with a specified frequency of checking.

• Example: driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);

An automation framework is a set of guidelines, best practices, and tools used for automated testing of software applications.

• Choose a programming language for writing test scripts (e.g. Java, Python)

• Select a testing tool for executing test scripts (e.g. Selenium, Appium)

• Implement page object model for better code organization

• Use data-driven testing for testing with multiple sets of data

• Incorporate reporting tools for tracking test results (e.g. ExtentReports)

React.js is a JavaScript library for building user interfaces.

• React.js is developed and maintained by Facebook.

• It allows developers to create reusable UI components.

• React.js uses a virtual DOM for efficient rendering.

• It follows a component-based architecture.

• React.js can be used for building single-page applications.

Common libraries used in testing include JUnit, TestNG, Selenium, Appium, and RestAssured.

• JUnit

• TestNG

• Selenium

• Appium

• RestAssured