What is the difference between functional and non-functional testing?
Theme: Software Testing Techniques Role: Qa Engineer/Test Engineer Function: Technology
Interview Question for QA Engineer/Test Engineer: See sample answers, motivations & red flags for this common interview question. About QA Engineer/Test Engineer: Ensure software quality through testing and quality assurance. This role falls within the Technology function of a firm. See other interview questions & further information for this role here
Sample Answer
Example response for question delving into Software Testing Techniques with the key points that need to be covered in an effective response. Customize this to your own experience with concrete examples and evidence
- Definition: Functional testing focuses on testing the functionality of a system or application, ensuring that it meets the specified requirements. Non-functional testing, on the other hand, focuses on testing the non-functional aspects of a system, such as performance, usability, security, and reliability
- Objective: Functional testing aims to validate that the system or application behaves as expected and meets the functional requirements. Non-functional testing aims to assess the quality attributes of the system, ensuring it performs well under different conditions
- Scope: Functional testing covers the specific features and functionalities of the system, ensuring they work correctly. Non-functional testing covers broader aspects like performance, scalability, security, usability, and compatibility
- Test Cases: Functional testing involves creating test cases based on functional requirements, focusing on inputs, outputs, and expected behavior. Non-functional testing involves creating test cases based on quality attributes, focusing on performance benchmarks, security vulnerabilities, usability guidelines, etc
- Testing Techniques: Functional testing typically involves techniques like unit testing, integration testing, system testing, and user acceptance testing. Non-functional testing involves techniques like performance testing, security testing, usability testing, and compatibility testing
- Tools: Functional testing can be performed using tools like Selenium, JUnit, TestNG, and Cucumber. Non-functional testing may require specialized tools like JMeter for performance testing, OWASP ZAP for security testing, and tools for usability testing
- Timing: Functional testing is usually performed early in the development lifecycle to ensure the core functionality is working. Non-functional testing is performed later in the lifecycle to assess the system's performance, security, and other non-functional aspects
- Impact on Users: Functional testing ensures that the system meets the users' functional requirements, providing a reliable and usable product. Non-functional testing ensures that the system performs well, is secure, and provides a good user experience
- Examples: Functional testing examples include testing login functionality, form validation, and data manipulation. Non-functional testing examples include load testing, security penetration testing, and accessibility testing
Underlying Motivations
What the Interviewer is trying to find out about you and your experiences through this question
- Knowledge & understanding: Assessing the candidate's understanding of the fundamental concepts and differences between functional and non-functional testing
- Experience: Evaluating the candidate's practical experience in conducting both functional and non-functional testing in previous roles
- Problem-solving skills: Assessing the candidate's ability to identify and address different types of testing requirements based on the nature of the system being tested
Potential Minefields
How to avoid some common minefields when answering this question in order to not raise any red flags
- Confusing or incorrect definitions: Providing inaccurate or unclear definitions of functional and non-functional testing
- Lack of understanding: Showing a lack of understanding of the fundamental differences between functional and non-functional testing
- Focusing only on functional testing: Neglecting to mention or downplaying the importance of non-functional testing in software development
- Inability to provide examples: Being unable to provide specific examples or scenarios that illustrate the differences between functional and non-functional testing
- Overgeneralization: Making broad statements without providing specific details or examples to support them
- Confusing functional & non-functional requirements: Mixing up or incorrectly identifying functional and non-functional requirements in relation to testing