Square India SDET Interview: Rounds, Questions and Preparation

What the job involves

An SDET (Software Development Engineer in Test) at global tech companies builds and maintains automated test frameworks, writes code to validate product functionality, and collaborates with developers to ensure quality at scale. Day to day, you might design test strategies, debug failures in CI/CD pipelines, and improve test coverage for web, mobile, or backend services. The role blends software engineering with quality assurance, requiring strong coding skills and a mindset for breaking systems.

Role and Technical Knowledge

1. 1

   What is the difference between a QA engineer and an SDET?

   A strong answer highlights that SDETs write production-grade automation code, build frameworks, and contribute to code reviews, while QA engineers may focus more on manual testing and test case execution.

2. 2

   Explain the test pyramid and how you would apply it in a microservices architecture.

   Cover unit tests at the base, integration tests in the middle, and UI tests at the top. For microservices, emphasize contract testing and API-level tests over brittle end-to-end UI tests.

3. 3

   How do you decide what to automate and what to leave for manual testing?

   Discuss factors like frequency of execution, stability of feature, cost of automation, and ROI. Mention that exploratory and usability tests often remain manual.

4. 4

   What are some common challenges in test automation for global-scale applications?

   Mention flaky tests, test data management, environment consistency, localization, and maintaining tests across multiple browsers and devices.

Practical Scenarios and Coding

1. 5

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

   Implement an efficient solution using a hash map. For testing, outline edge cases like empty string, all repeating characters, and special characters, and mention unit test cases.

2. 6

   Given a REST API endpoint, how would you design automated tests for it?

   Cover status codes, response schema validation, authentication, error handling, and performance. Mention using RestAssured or similar tools and integrating with CI.

3. 7

   You notice a test that passes locally but fails in CI. How do you debug it?

   Check for environment differences, timing issues, test data, and dependencies. Suggest adding logging, running in isolation, and using CI artifacts to reproduce.

4. 8

   How would you test a payment processing feature for an e-commerce app?

   Focus on security, idempotency, error handling, currency handling, and integration with third-party gateways. Mention both positive and negative scenarios.

Automation and Tools

1. 9

   What is the Page Object Model and why is it useful?

   Explain that it separates page structure from test logic, improving maintainability and reducing duplication. Mention how it aids in handling changes to UI.

2. 10

   How do you handle dynamic elements in Selenium?

   Discuss using explicit waits, XPath or CSS selectors with contains, and avoiding Thread.sleep. Mention strategies like waiting for element visibility or staleness.

3. 11

   What is the role of CI/CD in test automation?

   Explain that CI/CD ensures tests run automatically on code changes, providing fast feedback. Mention integrating test suites into pipelines and reporting results.

4. 12

   How would you test a mobile application differently from a web application?

   Cover device fragmentation, network conditions, gestures, battery usage, and app store guidelines. Mention tools like Appium and emulators/simulators.

Behavioural and HR

1. 13

   Tell me about a time you found a critical bug. How did you handle it?

   Use STAR method: describe the situation, your action in reporting and reproducing, and the outcome. Emphasize communication and preventing recurrence.

2. 14

   Why do you want to work as an SDET at a global tech company?

   Show passion for quality and automation, and mention the scale and impact of global products. Align your skills with the company's engineering culture.

3. 15

   Describe a situation where you had to learn a new technology quickly.

   Highlight your learning process, resources used, and how you applied it to a project. Show adaptability and self-motivation.

4. 16

   How do you handle disagreements with a developer about a bug's severity?

   Focus on data and user impact, not emotions. Mention collaborating to understand perspectives and escalating if needed with evidence.