Sinch India SDET Interview: Rounds, Questions and Preparation

What the job involves

As an SDET at a global tech company like Sinch, you will design, develop, and maintain automated test frameworks and test suites for APIs, microservices, and web applications. You will work closely with developers and product teams to ensure quality throughout the software development lifecycle, often contributing to CI/CD pipelines and performance testing. The role blends software engineering skills with testing expertise, requiring you to write production-grade code for test automation.

Role and Technical Knowledge

1. 1

   What is the difference between a test case and a test scenario? Give an example relevant to an API like a user registration endpoint.

   A strong answer defines test scenario as a high-level objective (e.g., verify user registration) and test case as detailed steps with input data and expected results (e.g., POST /register with valid email and password returns 201).

2. 2

   Explain how you would design a test automation framework for a microservices-based application using Selenium and REST Assured.

   Cover modular structure, page object model for UI, separate API test layer, data-driven approach, reporting (e.g., ExtentReports), and integration with CI/CD.

3. 3

   What are the key differences between smoke, sanity, and regression testing? When would you run each in a CI pipeline?

   Smoke tests validate critical functionality after a build, sanity tests check specific fixes, and regression tests ensure no side effects. In CI, smoke runs on every commit, sanity on bug fixes, and regression before release.

4. 4

   How do you handle dynamic elements in Selenium? Name at least two strategies.

   Use explicit waits (WebDriverWait) with expected conditions, and locate elements using relative XPath or CSS selectors that do not depend on dynamic attributes like IDs.

Practical Scenarios

1. 5

   You are testing a payment API that sometimes returns a 500 error under load. How would you investigate and report this issue?

   Describe checking logs, reproducing with load testing tools (e.g., JMeter), isolating whether it is a server or test script issue, and reporting with steps, expected vs actual, and environment details.

2. 6

   Your automated test suite passes locally but fails in the CI environment. What could be the reasons and how would you debug?

   Consider environment differences (OS, browser versions, network), test data setup, timing issues, and CI configuration. Suggest adding logging, screenshots on failure, and running tests in a containerized environment.

3. 7

   How would you test a REST API endpoint that sends OTP via SMS for user verification? Outline your test cases.

   Cover valid and invalid phone numbers, rate limiting, OTP expiry, re-send functionality, response codes, and integration with a mock SMS service to avoid sending real messages.

4. 8

   You need to test a feature that is not yet fully developed. How do you proceed with automation?

   Suggest using mocks or stubs for unavailable components, writing tests based on API contracts, and collaborating with developers to understand expected behavior. Emphasize iterative development of tests.

Behavioural and HR

1. 9

   Tell me about a time you found a critical bug late in the development cycle. How did you handle it?

   Use STAR method: describe the situation, your action (e.g., immediately reported with evidence, helped triage), and the result (e.g., bug fixed before release, process improved).

2. 10

   Why do you want to work as an SDET rather than a pure developer or manual tester?

   Show passion for quality and automation, mention enjoyment of coding and breaking software, and highlight career growth in test automation and DevOps.

3. 11

   Describe a situation where you had to learn a new testing tool or technology quickly. How did you approach it?

   Give a specific example, such as learning REST Assured for API testing, and explain your learning method (documentation, tutorials, practice) and the outcome.

4. 12

   How do you handle disagreements with a developer who claims your reported bug is not reproducible?

   Emphasize clear communication, providing detailed steps and evidence (logs, screenshots), and collaborating to reproduce together. Focus on resolving the issue, not blaming.

Coding and Automation

1. 13

   Write a Java method to check if a string is a palindrome, ignoring case and non-alphanumeric characters.

   Use two pointers or reverse string approach, handle edge cases like empty string, and discuss time complexity O(n).

2. 14

   Given a list of integers, write a function to return the duplicate elements using a HashSet in Python.

   Iterate through list, add to set, and collect elements already in set. Explain why HashSet gives O(n) time complexity.

3. 15

   How would you automate a login page using Selenium WebDriver? Write a short code snippet or describe the steps.

   Mention locating username and password fields, using sendKeys, clicking login button, and asserting successful login via URL or element presence. Use Page Object Model if possible.

4. 16

   Explain how you would use TestNG annotations to set up and tear down a test environment.

   Describe @BeforeSuite, @BeforeClass, @BeforeMethod, @AfterMethod, etc., and how they help in initializing WebDriver, opening browser, and closing resources.