Census India SDET Interview: Rounds, Questions and Preparation

What the job involves

As an SDET at a fast-growing global tech company, you will design, build, and maintain automated test frameworks and suites that validate web, API, and data pipelines. You will work closely with developers and product managers to catch issues early, improve release confidence, and reduce manual regression effort. Day to day, you will write code in languages like Java or Python, integrate tests into CI/CD, and investigate failures across distributed systems.

Role and Technical Knowledge

1. 1

   What is the difference between a QA Engineer and an SDET, and why does a company like Census India need SDETs?

   Explain that SDETs write production-quality test code, build frameworks, and automate at scale, while QA focuses more on manual and exploratory testing. Link to fast-growing product teams needing reliable releases.

2. 2

   How would you design a test automation framework for a web application that has both UI and REST APIs?

   Cover layered design: page objects for UI, API clients for services, reusable utilities, configuration management, and reporting. Mention parallel execution and CI integration.

3. 3

   Explain the test pyramid and how you would apply it to a data-heavy product.

   Describe many unit tests, fewer integration and API tests, and minimal UI tests. Add data validation tests at the database layer and contract tests for APIs.

4. 4

   What is idempotency in API testing, and why does it matter for a global tech product?

   Define idempotency as repeating the same request without changing the result. Explain its importance for retries, payments, and distributed systems reliability.

Practical Scenarios and Debugging

1. 5

   A Selenium test passes locally but fails in CI. How would you debug it?

   Check environment differences, browser and driver versions, headless mode, timeouts, test data, and CI logs or screenshots. Suggest adding explicit waits and stable selectors.

2. 6

   You find a bug that only happens for users in a specific timezone. How do you reproduce and report it?

   Mention setting the timezone in test data or browser, checking date handling in code and database, and writing a clear bug report with steps, expected vs actual, and impact.

3. 7

   How would you test a REST API endpoint that returns a list of records with pagination and filters?

   Cover status codes, response schema, pagination boundaries, filter combinations, sorting, empty results, and error cases like invalid parameters.

4. 8

   A flaky test is failing 1 in 10 runs. What steps would you take to fix it?

   Identify race conditions, hard waits, shared state, or external dependencies. Suggest retries only as a temporary measure and fixing root cause with better waits or isolation.

Coding and Automation Fundamentals

1. 9

   Write a function to find the first non-repeating character in a string. How would you test it?

   Discuss time and space complexity, edge cases like empty string, all repeating characters, and unicode. Show unit tests for normal and boundary inputs.

2. 10

   How do you handle dynamic elements in Selenium?

   Use relative locators, CSS or XPath with stable attributes, explicit waits, and avoid brittle indexes. Mention PageFactory or custom wait utilities.

3. 11

   Given a table of user orders, write a SQL query to find customers with more than three orders in the last month.

   Use GROUP BY, HAVING, and date functions. Explain how you would validate the query result against application data.

4. 12

   How would you integrate automated tests into a CI/CD pipeline for a microservices product?

   Describe stages: build, unit tests, API tests, UI tests, and deployment gates. Mention parallel jobs, test reports, and failing fast on critical tests.

Behavioural and HR Questions

1. 13

   Tell me about a time you found a critical bug late in a project. What did you do?

   Use STAR format: situation, task, action, result. Highlight communication, quick reproduction, and preventing recurrence with a test.

2. 14

   Why do you want to join a fast-growing global tech company like Census India as an SDET?

   Connect your interest in automation, scale, and global products. Mention learning opportunities and contributing to release quality.

3. 15

   Describe a situation where you disagreed with a developer about whether something was a bug. How did you handle it?

   Show empathy, data-driven discussion, and focus on user impact. Mention reproducing with evidence and agreeing on a fix or workaround.

4. 16

   Where do you see yourself in three years as an SDET?

   Talk about deepening automation and coding skills, owning test infrastructure, and mentoring juniors. Align with company growth and quality goals.