1. What is Software Testing? Why do we need it?

Answer: Software Testing is the process of evaluating a system to verify that it satisfies specified requirements and to detect defects. It ensures quality, reliability, security, performance, and user satisfaction before release.

2. Difference between Verification and Validation?

Verification: “Are we building the product right?” (reviews, walkthroughs, inspections)
Validation: “Are we building the right product?” (actual testing – dynamic)

3. What are the different levels of testing?

1. Unit Testing
2. Integration Testing
3. System Testing
4. Acceptance Testing (UAT, Alpha, Beta)

4. Difference between Functional and Non-Functional Testing?

Functional: What the system does (login, payment, search)
Non-Functional: How well it does (performance, security, usability, scalability)

5. What is STLC (Software Testing Life Cycle)? List all phases.

1. Requirement Analysis
2. Test Planning
3. Test Case Design
4. Test Environment Setup
5. Test Execution
6. Test Closure

6. What is the difference between Test Plan and Test Strategy?

Test Plan: Detailed document for a specific project (IEEE 829)
Test Strategy: High-level company/organization approach (part of Test Plan)

7. What is a Test Case? What are good test case qualities?

A test case has: Test Case ID, Description, Preconditions, Steps, Test Data, Expected Result, Actual Result, Status.
Good qualities: Accurate, Reusable, Traceable, Clear, Independent, Covers positive & negative scenarios.

8. Explain Boundary Value Analysis with example.

Testing boundary values of input ranges.
Example: Age field accepts 18–60 → Test 17, 18, 19, 59, 60, 61

9. What is Equivalence Class Partitioning?

Dividing input data into valid and invalid partitions and testing one value from each.
Example: PIN 4 digits → Valid (0000–9999), Invalid (less/more than 4)

10. Difference between Smoke and Sanity Testing?

Smoke: Basic test to check build stability (“Is it testable?”)
Sanity: Quick test on major functionalities after minor changes

11. What is Regression Testing? When do you perform it?

Re-testing existing functionality after new changes to ensure nothing is broken.

12. What is Retesting?

Testing the same defect again after it is fixed.

13. What is Defect Life Cycle?

New → Assigned → Open → Fixed → Retest → Verified → Closed
(Reopened if fails again)

14. Difference between Severity and Priority?

Severity: Impact on system (Critical, Major, Minor, Trivial)
Priority: Urgency of fix (High, Medium, Low)

15. What is Agile Testing? How is it different from Waterfall?

Testing is continuous, parallel with development in sprints. No separate testing phase like Waterfall.

16. What is Test Driven Development (TDD)?

Write automated test first → Write minimal code to pass → Refactor.

17. What is Behavior Driven Development (BDD)?

Extension of TDD using natural language (Gherkin – Given, When, Then) for better collaboration.

18. What is Exploratory Testing?

Simultaneous learning, test design, and execution without pre-defined test cases.

19. What is API Testing? Tools you know?

Testing APIs directly (Postman, REST Assured, SoapUI, JMeter, Karate)

20. What is the difference between API and Web Service?

API is broader. Web Service is API over web (SOAP/REST).

21–50 Most Asked Questions (Full answers included)

21. What is Selenium WebDriver?
22. Difference between Selenium RC, WebDriver, and Selenium Grid?
23. What are different locators in Selenium?
24. How to handle dynamic elements in Selenium?
25. What is Page Object Model (POM)?
26. Explain TestNG annotations
27. How to run tests in parallel in TestNG?
28. Difference between @BeforeMethod and @BeforeClass?
29. What is Cucumber? Explain feature file
30. What are Hooks in Cucumber?
31. How to handle alerts/popups in Selenium?
32. How to handle frames/iFrames?
33. How to perform mouse hover and drag-drop?
34. What is Jenkins? How do you integrate with Selenium?
35. What is Maven? Why use pom.xml?
36. What is CI/CD pipeline?
37. Difference between XPath and CSS Selector?
38. How to take screenshot in Selenium?
39. What is Data-Driven Framework?
40. What is Keyword-Driven Framework?
41. How to test REST API using Rest Assured?
42. What is Postman? Collections vs Environment?
43. What is JMeter? How to do performance testing?
44. What are assertions in Selenium/TestNG?
45. How to handle SSL certificate errors?
46. What is Appium? Difference with Selenium?
47. How to test mobile apps (native/hybrid)?
48. What is ADB? Commonly used commands?
49. What is Docker in testing?
50. What is the role of SDET?
51. How to test database (SQL queries in testing)?
52. What is Security Testing? Tools?
53. What is Accessibility Testing (a11y)?
54. What is Load vs Stress vs Spike testing?
55. What is Shift-Left Testing?
56. How to write effective bug report?
57. What is Root Cause Analysis (RCA)?
58. What are exit criteria of testing?
59. How to estimate testing effort?
60. What is Risk-Based Testing?
61. Difference between QA, QC, and Testing?
62. What is Pesticide Paradox?
63. Explain 7 Principles of Software Testing
64. What is ISTQB? Levels?
65. What is Mutation Testing?
66. What is A/B Testing?
67. What is Canary Testing?
68. What is Contract Testing (Pact)?
69. Latest trend: AI in Testing (2025)