Stelo Technology

Difference Between Functional and Non-Functional Testing

Functional and Non-Functional Testing

Software testing is an important phase of the software development cycle. It ensures that applications are reliable and functional. Functional and non-functional tests are important among the different testing methodologies.

It is important for stakeholders, developers, and testers to understand the differences between functional and non-functional testing.

What is functional testing?

Functional testing is concerned with verifying the software’s ability to meet specified requirements. This involves testing an application against functional specifications to ensure that all features are working as intended. This type of test answers the question “Does software work as intended?”

Subscribe to our Newsletter

The Key Aspects Of Functional Testing

  1. User Interface Testing
    • Verify that the user interface of the application behaves as it should.
    • Verifies interactive elements, such as buttons and menus.
  2. Unit Testing
    • Test individual software units or components to make sure they work correctly.
    • Developers typically perform this task during the coding stage.
  3. Integration Testing
    • Verify that the different modules or services work as expected.
    • Identifies problems in the interaction of integrated units.
  4. System Testing
    • Validates the entire and integrated software application.
    • Verify that the software meets all the requirements.
  5. Regression Testing
    • Confirm that the new code has not negatively affected existing functionality.
    • After updates, bug fixes, and enhancements.

Examples of Functional Testing

  • Verifying a login function allows users to enter credentials and access system.
  • Verify that the search function returns relevant results according to user queries.
  • Assuring that the shopping cart updates its total price accurately when an item is added or removed.

What is non-functional testing?

Non-functional testing is the evaluation of aspects of software that are not related to specific behavior or functions. It assesses performance, usability and reliability, among other quality attributes. Non-functional Testing answers the question “How does the software perform in different conditions?”

The Key Aspects Of Non-Functional Tests:

  1. Performance Testing
    • Measuring the performance of software under various workloads.
    • Includes stress testing and load testing.
  2. Tests of Usability:
    • Assess the user-friendliness and usability of the application.
    • The ease of use and interaction with the software is assessed.
  3. Security Testing
    • This tool identifies vulnerabilities and makes sure that the application is protected against threats.
    • Includes penetration testing as well as vulnerability assessments.
  4. Compatibility testing:
    • Test the performance of your software across multiple environments, browsers and devices.
    • Consistency and reliability are ensured in different setups.
  5. Reliability testing:
    • Test the software to see if it performs consistently over time.
    • Test the robustness and stability of your application.

Non-functional Testing Examples:

  • Measuring response times of a site under high traffic conditions.
  • Evaluation of the ease-of-use of an app’s user interface for new users.
  • Test the software for resistance to cyber attacks and data breaches.

Ready to enhance your software quality and accelerate your time to market? Contact us today at to request a customized quote for your business!

The Differences between Functional and Non-Functional Tests

  1. Focus and Objectives
    • Functional Testing: Focuses on specific actions and features of the software. Checks to see if the application is performing tasks according to the requirements.
    • Non-Functional Tests: These tests focus on the quality of the software as a whole, including performance, usability and security.
  2. Testing Approach
    • Functional Testing: This is a type of testing that involves either manual or automated scripts. The tests are usually based upon user stories, use case scenarios, or requirements.
    • Non-Functional Tests: These tests require specialized tools and methods to evaluate aspects such as performance, security and non-functionality. The tests are usually scenario-based.
  3. Outcome:
    • Functional Testing: The result is a pass/fail outcome depending on whether or not the application meets its functional requirements.
    • Non-Functional Tests: These tests provide insights into the performance and quality of software. They often result in performance metrics, scores for usability, or security assessments reports.
  4. The Development Lifecycle:
    • Functional Testing: Perform throughout the development cycle. Particularly during the unit integration and system testing phases.
    • Non-Functional Tests: These are usually conducted after functional tests, during the last stages of development and in a testing phase.

The importance of both types of testing

Functional and non-functional tests are both essential to deliver a robust, reliable software product. Functional testing is used to ensure that software will perform its intended function, while non-functional tests are used to verify that software meets user expectations and quality standards.

Combining both testing types:

  1. Comprehensive Quality Assurance
    • By integrating both types of testing, you can ensure that the software is thoroughly tested.
  2. Enhance User Experience
    • Non-functional testing improves usability, performance and usability.
  3. Risk Mitigation:
    • Early identification and resolution of both functional and nonfunctional issues reduces the likelihood of critical failures after deployment.
  4. Customer satisfaction:
    • Delivering a product that is reliable, secure and performs well increases customer satisfaction and loyalty.

The conclusion of the article is:

It is important to understand the difference between non-functional and functional testing for software development. Functional testing is concerned with verifying the software’s ability to perform its intended task, while non-functional tests ensure that it meets the quality standards for performance, usability and security. Combining both testing methods, developers and testers are able to create a high-quality, well-rounded software product that will meet user expectations and stand the test of time.

Ready for Free Consultation ?

Book a call with Experts