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Top 100 Test Engineer Interview Questions and Answers

Top 100 Test Engineer Interview Questions and Answers

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1. What is Software Testing?

Answer:
Software testing is the process of evaluating and verifying that a software product or application meets specified requirements and identifying defects. It ensures the software is error-free and achieves the desired output.

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2. Differentiate between White Box and Black Box Testing.

Answer:
White Box Testing involves testing the internal structures or workings of an application, often requiring code knowledge. Black Box Testing tests the application’s functionality without knowing its internal structures.

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3. What is Regression Testing?

Answer:
Regression testing ensures that recent code changes haven’t adversely impacted existing functionalities. It’s repeated testing of an already tested program, after modification.

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4. What is a Test Case?

Answer:
A test case specifies the input, action (or event), and an expected response, to determine if a feature of an application functions correctly.

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5. Explain Selenium and its components.

Answer:
Selenium is a suite of tools for automating web browsers. Components include:

  • Selenium IDE: Browser plugin for record-playback testing.
  • Selenium WebDriver: API for browser automation.
  • Selenium Grid: Allows concurrent test execution across machines.

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6. What’s the difference between assert and verify commands?

Answer:
In testing frameworks, assert stops test execution if the assertion fails, while verify continues execution even if the assertion fails, logging the failure.

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7. Explain the concept of Defect Lifecycle.

Answer:
Defect lifecycle details the various stages a defect goes through, from discovery to resolution. Stages include: New, Open, Fixed, Retest, Verified, Closed, Reopen.

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8. How do you prioritize test cases?

Answer:
Prioritize based on:

  • Business impact
  • Critical and complex functionalities
  • Modules frequently changed
  • Past defect history

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9. What is Load Testing?

Answer:
Load testing checks the system’s behavior under a specific load, determining how it handles many users simultaneously.

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10. What is the Pesticide Paradox in testing?

Answer:
Pesticide Paradox states that repeatedly using the same tests will no longer find new defects. To overcome this, tests should be regularly reviewed and revised.

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11. Describe Boundary Value Analysis (BVA).

Answer:
BVA is a technique where test cases are generated using boundary values. If a field accepts numbers 1-100, test cases would use values 0, 1, 100, and 101.

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12. What is a Test Harness?

Answer:
A test harness encompasses the overall test environment where testing takes place, including test tools and test data.

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13. What is the Page Object Model in Selenium?

Answer:
Page Object Model (POM) is a design pattern to create object repositories for web UI elements. Each web page is represented as a class, separating page actions from tests.

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14. Explain a “stale element” reference in Selenium.

Answer:
A “stale element” reference occurs when an element is no longer present in the DOM due to page refresh or modification. Selenium can’t interact with stale elements.

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15. What is exploratory testing?

Answer:
Exploratory testing is an unscripted approach where testers explore the application and simultaneously design and execute tests based on findings.

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16. What is a Test Suite?

Answer:
A test suite is a collection of test cases intended to test a behavior or a set of behaviors of an application.

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17. What’s the significance of a Testing Pyramid?

Answer:
The Testing Pyramid visualizes different layers of tests: unit tests at the base, service tests in the middle, and UI tests at the top. It emphasizes having more unit tests and fewer UI tests for cost-effective and stable test automation.

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18. What is Risk-based Testing?

Answer:
Risk-based testing prioritizes testing functionalities based on the risk factor. High-risk functionalities, those affecting business or having a history of defects, are tested first.

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19. Explain Mutation Testing.

Answer:
Mutation testing introduces small changes (mutations) to the source code and checks if the tests detect these changes. It evaluates the quality of the existing tests.

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20. What is a Test Double?

Answer:
Test doubles are used to isolate units of code during testing. Examples include mocks, stubs, and fakes. They simulate the behavior of real components.

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21. What is Smoke Testing?

Answer:
Smoke testing, often called “build verification testing”, is a preliminary test to check the basic functionality of an application. It ensures the software is stable for further testing.

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22. What is Continuous Integration?

Answer:
Continuous Integration (CI) involves integrating code changes frequently, usually multiple times a day, to detect integration issues early.

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23. How do you handle flaky tests?

Answer:
To handle flaky tests:

  • Isolate and rerun them to confirm flakiness.
  • Investigate root causes (timing issues, external dependencies).
  • Fix the root cause or, if needed, temporarily disable and log them.

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24. What is Equivalence Partitioning?

Answer:
Equivalence Partitioning divides input data into equivalent classes to reduce the number of test cases. If a test case from one partition passes, others from the same partition are likely to pass.

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25. What is a Test Environment?

Answer:
A test environment is a setup where testing occurs. It includes hardware, software, network configurations, server settings, and tools, resembling the production environment.

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26. What are non-functional tests?

Answer:
Non-functional tests evaluate the system’s non-functional attributes like performance, usability, and reliability, ensuring the system meets specific criteria besides functionality.

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27. How is code coverage useful in testing?

Answer:
Code coverage measures the amount of code exercised by tests. While it doesn’t guarantee quality, higher coverage can indicate better-tested software.

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28. What is Agile Testing?

Answer:
Agile testing aligns with Agile software development. Testing is continuous, and feedback is rapid, aligning with iterations or sprints.

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29. How do you ensure mobile app testing comprehensiveness?

Answer:
Test on various devices, OS versions, screen sizes, and resolutions. Use emulators/simulators and physical devices. Address different network conditions and perform usability, security, and compatibility tests.

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30. What is a Test Automation Framework?

Answer:
A test automation framework provides a set of guidelines, coding standards, and concepts for creating test cases. Examples include Data-Driven, Keyword-Driven, and Page Object Model frameworks.

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31. What is Stress Testing?

Answer:
Stress testing evaluates system behavior under intense loads, beyond its specifications, to determine its breaking point or ensure it gracefully degrades.

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32. Explain Test Driven Development (TDD).

Answer:
In TDD, tests are written before actual code. The process is:

  1. Write a failing test.
  2. Write code to pass the test.
  3. Refactor code for optimization.

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33. What is Usability Testing?

Answer:
Usability testing evaluates the product’s user interface and overall user experience. Real users perform tasks, and testers identify problems in user interactions.

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34. How do you handle dependencies in test automation?

Answer:
Use mock objects or stubs to simulate dependencies, ensuring tests run in isolation. Dependency injection frameworks can also help manage dependencies.

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35. What are heuristics in testing?

Answer:
Heuristics are experience-based techniques or rules of thumb used for problem-solving in testing. They guide testers in the absence of detailed requirements.

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36. Explain a “Happy Path” in testing.

Answer:
The “Happy Path” refers to a default scenario featuring no invalid or unexpected input. It tests the flow that works, assuming perfect user behavior.

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37. What is a Test Plan?

Answer:
A test plan is a detailed document that outlines the test strategy, objectives, schedule, estimation, deliverables, and resources required for testing.

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38. What is Monkey Testing?

Answer:
Monkey testing involves random testing without any predefined test cases or systematic approach. It checks for system crashes with random inputs.

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39. What is Performance Testing?

Answer:
Performance testing checks the speed, responsiveness, and stability of a system under load. It identifies bottlenecks, performance issues, and system behavior.

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40. What are Selenium Waits?

Answer:
Waits in Selenium handle synchronization issues between test execution and web application’s behavior. Types include “Implicit Wait”, “Explicit Wait”, and “Fluent Wait”.

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41. What is Compatibility Testing?

Answer:
Compatibility testing checks if the software runs as expected on different browsers, OS, devices, and network environments.

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42. How is Alpha Testing different from Beta Testing?

Answer:

Alpha testing is conducted by developers or testers within the organization. Beta testing is conducted by potential users or customers in a real-world environment.

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43. What is a Test Scenario?

Answer:
A test scenario describes the functionality to be tested. It’s a high-level overview, while test cases provide detailed test steps.

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44. Explain Concurrency Testing.

Answer:
Concurrency testing, or multi-user testing, checks the effects of accessing the application simultaneously by multiple users, ensuring multiple processes run without issues.

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45. What is End-to-End Testing?

Answer:
End-to-end testing verifies the complete application flow, from start to end, ensuring the entire process of inputs, outputs, and interactions work smoothly.

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46. What is the V-Model in testing?

Answer:
The V-Model, or Verification and Validation model, represents each development stage (Verification) corresponding to a testing phase (Validation).

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47. What is a Test Bed?

Answer:
A test bed is the test environment where testing occurs. It includes software, hardware, network configurations, and the test data.

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48. What is Ad Hoc Testing?

Answer:
Ad Hoc testing is an informal testing type without any specific test case intent, test design, or test planning.

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49. What is A/B Testing?

Answer:
A/B testing, or split testing, compares two versions of a webpage or app to determine which one performs better in terms of user engagement or other KPIs.

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50. What are the principles of good testing?

Answer:
Principles include:

  • Testing shows defects presence, not their absence.
  • Exhaustive testing is impossible.
  • Early testing is beneficial.
  • Defect clustering (80/20 rule).
  • Pesticide paradox.
  • Testing is context-dependent.

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51. What is the difference between Static and Dynamic Testing?

Answer:
Static testing involves reviewing code, documentation, or requirements without executing the program. Dynamic testing involves actual program execution.

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52. What is Pairwise Testing?

Answer:
Pairwise (or All-Pairs) testing is a method to test all possible discrete combinations of input parameters, ensuring each pair is tested at least once.

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53. What is Database Testing?

Answer:
Database testing verifies the schema, tables, triggers, etc., of the database under test. It checks data integrity, consistency, and validation.

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54. What is Volume Testing?

Answer:
Volume testing checks the system’s behavior by populating the database with a large volume of data and evaluating its handling capability.

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55. What is Security Testing?

Answer:
Security testing evaluates the system’s ability to safeguard data. It ensures protection against threats, unauthorized access, and other vulnerabilities.

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56. What are CRUD tests?

Answer:
CRUD tests validate the Create, Read, Update, and Delete operations of an application, ensuring data manipulation processes are error-free.

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57. What is Scalability Testing?

Answer:
Scalability testing determines the software’s capacity to handle increased loads, like more users, transactions, or data, without performance degradation.

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58. What is the difference between Severity and Priority?

Answer:
Severity indicates the impact of a defect on system functionality. Priority indicates the urgency to fix a defect based on its business impact.

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59. What is a Test Strategy?

Answer:
A test strategy is a high-level document defining the testing approach and objectives. It outlines test levels, tools, resources, risks, and scope of testing.

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60. What is a Test Stub?

Answer:
A test stub is a minimal implementation of a component, allowing testing of a component in isolation, especially when called functionalities are not yet developed.

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61. What is Spike Testing?

Answer:
Spike testing assesses system behavior under sudden increases and decreases in user load, verifying system robustness during traffic spikes.

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62. What is State Transition Testing?

Answer:
State Transition Testing evaluates system behavior for different input conditions in a sequence, using a state transition diagram.

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63. What is a Test Driver?

Answer:
A test driver is a program or script developed to initiate and control test execution, especially when a module is not yet developed.

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64. What is the difference between Verification and Validation?

Answer:
Verification ensures the product is built correctly, aligning with specified requirements. Validation ensures the right product is built, meeting user needs.

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65. What is API Testing?

Answer:
API (Application Programming Interface) Testing involves testing APIs directly and as a part of integration testing to check if they meet functionality, reliability, and security requirements.

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66. What are Post-conditions in test cases?

Answer:
Post-conditions describe the state of the system after the test case has been executed. It ensures the system returns to its desired state post testing.

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67. What is a Test Matrix?

Answer:
A test matrix is a table used to capture test cases based on variables or conditions, ensuring thorough testing for each combination.

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68. What is GUI Testing?

Answer:
GUI (Graphical User Interface) Testing ensures the visual elements of an application function correctly and are user-friendly.

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69. How is Failover Testing conducted?

Answer:
Failover testing checks system resilience by simulating component failures and ensuring system switchovers without service disruption.

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70. What is Conformance Testing?

Answer:
Conformance testing verifies if a product meets its specified standards, ensuring compatibility and interoperability with other products.

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71. What is Regression Testing?

Answer:
Regression testing ensures that recent code changes haven’t affected existing functionalities. It checks if previous functionalities still work after a new release.

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72. What are Test Suites?

Answer:
A test suite is a collection of related test cases bundled together. Running a test suite allows for grouped execution of multiple test cases.

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73. What is Load Testing?

Answer:
Load testing checks system behavior under a specific load, simulating multiple users accessing the application simultaneously.

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74. How do you manage test data?

Answer:
Test data can be managed using:

  • Data masking to secure sensitive data.
  • Data subsetting to create smaller, representative data samples.
  • Automation tools to generate and maintain data.

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75. What is Boundary Value Analysis?

Answer:
Boundary Value Analysis is a technique to test boundary values of acceptable input ranges. It’s based on the principle that errors often occur at the boundaries.

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76. What is Component Testing?

Answer:
Component testing, or unit testing, involves testing individual components in isolation, ensuring each functions correctly. It is typically automated and performed by developers.

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77. What is a Test Harness?

Answer:
A test harness includes the test data and set of test scripts on which tests will be executed. It facilitates automated testing by setting the preconditions for tests.

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78. What is Soak Testing?

Answer:
Soak testing involves testing a system under continuous load over an extended period to identify performance issues that arise over time.

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79. What is a Test Oracle?

Answer:
A test oracle is a mechanism, principle, or tool used to determine whether a test passed or failed by comparing expected and actual outcomes.

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80. What is Exploratory Testing?

Answer:
Exploratory testing is a type of testing where test cases aren’t predefined. Testers explore the application, learning and designing test cases based on their findings.

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81. What is Recovery Testing?

Answer:
Recovery testing assesses how quickly and effectively a system can recover after it crashes or encounters a significant error.

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82. What is Installation Testing?

Answer:
Installation testing ensures that software installs successfully in the target environment and works as intended post-installation.

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83. What is White Box Testing?

Answer:
White Box Testing, or Glass Box Testing, involves testing the internal logic and structure of the code. It’s usually performed by developers with knowledge of the codebase.

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84. What are Test Deliverables?

Answer:
Test deliverables are documents and artifacts produced during the testing process, including test plans, test cases, test scripts, and defect reports.

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85. What is Gray Box Testing?

Answer:
Gray Box Testing is a combination of Black Box and White Box Testing. It tests the application based on partial knowledge of its internal workings.

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86. What is a Defect Life Cycle?

Answer:
Defect Life Cycle, or Bug Life Cycle, is the progression of a defect from its discovery to its closure. It includes stages like New, Assigned, Resolved, and Closed.

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87. What is a Test Closure Document?

Answer:
A test closure document, part of the test closure phase, captures the end-of-test activities. It includes a summary of testing, defect metrics, and lessons learned.

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88. What is Black Box Testing?

Answer:
Black Box Testing evaluates system functionality without considering its internal code structure. Tests are based on software requirements and specifications.

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89. What is Gorilla Testing?

Answer:
Gorilla Testing involves repeatedly testing one functionality or module of the application exhaustively to ensure its robustness and reliability.

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90. How do you perform Backend Testing?

Answer:
Backend testing focuses on the server-side. It includes:

  • Database testing.
  • Checking data integrity.
  • Performing CRUD operations.
  • Validating stored procedures and triggers.

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91. What is a Test Bed?

Answer:
A test bed is an environment configured for testing. It includes software, hardware, network configurations, and tools used for testing.

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92. What is Context-Driven Testing?

Answer:
Context-driven testing focuses on creating test strategies responsive to the project’s specific context or environment. It relies heavily on testers’ expertise and understanding of the situation.

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93. What is a Test Case?

Answer:
A test case is a set of conditions under which a tester will determine if a specific feature of an application functions correctly.

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94. What is Error Guessing?

Answer:
Error guessing is a test technique where testers use their experience to guess where defects may be present and design tests accordingly.

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95. What is a Bug Triage?

Answer:
Bug triage is a process where the severity, impact, and priority of a defect are determined. It helps in deciding the order in which defects should be fixed.

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96. What is Mutation Testing?

Answer:
Mutation testing is a technique to assess the effectiveness of test cases. It involves introducing small code changes (mutations) and checking if test cases detect them.

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97. What is Compatibility Testing?

Answer:
Compatibility testing checks if software operates correctly on different hardware, OS versions, browsers, and network environments.

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98. What is Branch Testing?

Answer:
Branch testing ensures that each branch of decision-making (like if-else conditions) in the code is tested at least once.

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99. What is a Test Harness?

Answer:
A test harness facilitates automated testing by setting up the necessary prerequisites. It includes test data, mock objects, and configured test environment.

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100. What is a Test Scenario?

Answer:
A test scenario describes a functionality that can be tested. It provides a high-level overview, while test cases provide detailed steps.

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