Updated March 27, 2023
Difference Between Functional Testing vs Non-Functional Testing
Functional Testing vs Non-functional Testing are two critical forms of software testing essential to the app development process.
There are several tools available in the market for software testing. As such, the most popular tools for functional testing are Selenium and Sauce Labs, while non-functional testing tools include JMeter and Loadster.
Whether it is software, application, or website development, software testing is paramount to attain defect-free and smooth running of products. It is a process that checks the quality of the product to find whether the developed software or application meets the specified requirements or not. Apart from quality, testing can also remove most of the bugs and errors from the software. Software Testing is classified as Functional Testing and Non-functional Testing, which have distinct advantages, benefits, and features.
Table of Contents
- Introduction
- Understanding Functional Testing vs Non-Functional Testing
- Functional Testing
- Non-functional Testing
- Head-to-Head Comparison Infographic
- Key Differences
- Comparison Table
- Examples
- Final Thoughts
- Frequently Asked Questions (FAQs)
- Recommended Articles
Key Highlights
- Functional testing determines whether the software program meets the requirements.
- Non-functional testing examines the software’s usability, reliability, performance, and other non-functional elements.
- Functional testing focuses on what the software does, whereas non-functional testing focuses on how well the software performs it.
- Functional testing focuses on the expected outcomes, whereas non-functional testing focuses on the quality of those results.
- Since the software’s functioning should be verified before evaluating its performance or other non-functional characteristics, functional testing is typically conducted before non-functional testing.
Understanding Functional Testing vs Non-Functional Testing
Both types of testing have their applications in various domains, such as healthcare, finance, e-commerce, and more. They are essential for ensuring the software meets user expectations and performs optimally in real-world scenarios.
Functional Testing
- Functional testing is a type of software testing that verifies whether an application meets its intended functional requirements.
- Example: testing whether a login page allows a user to log in successfully or whether a search function returns accurate results.
- Functional testing verifies the ‘Functionality’ of the software or application under test. It ensures that each product function operates in conformance with the requirement specification.
- Functional testing is carried out to describe the behavior and execution of the software system.
- Before performing the non-functional test, it is essential to conduct functional testing to understand how the system executes its function efficiently.
Non-Functional Testing
- Non-functional testing verifies the non-functional aspects like usability, reliability, and software or application performance.
- Example: testing whether a website can handle high traffic or whether it is user-friendly.
- It focuses on all the aspects which are not addressed in the functional testing.
- When a product runs as per the consumer’s expectation and is efficient under any circumstances, it is considered reliable.
- Non-functional testing is carried out under these parameters of customer experience.
- As it’s not feasible to carry out non-functional testing manually, some special automated tools are used in this type of testing.
Head-to-Head Comparison Between Functional vs Non-Functional Testing (Infographics)
Below are the top 10 differences between Functional testing vs Non-functional testing
Key Differences Between Functional vs Non-Functional Testing
1. Motive
- Motive is the objectives for which each of these is used are very different.
- Functional testing is used to verify the demands and requirements that the system is supposed to meet are met correctly.
- It is used to check that the software application does not have any bugs and aids in the decision-making about its release and promotion of it.
- On the contrary, non-functional testing aims to see if the application performs as the customer expects it by examining the user experience.
- In this, response time to perform the tasks or to the customer’s request is also assessed.
2. Testing Techniques/Sub-tests
Under functional testing, the sub-tests performed include:-
- Unit testing for checking errors and bugs from the initial stage of developing the application.
- Smoke and sanity test to ensure the software works per the specifications.
- White-box test for the examination of code.
- Black-box test by running test cases on the system
- Integration test for checking that all components interact as they are expected to with each other, etc.
For non-functional testing, the sub-tests performed include:-
- Performance test for quality.
- Load test for behavior under normal as well as extreme conditions.
- Compatibility test.
- Configuration test.
- Test for stress to check its limits.
- Security test.
- Scalability test.
- Recovery test to check for recovery duration in case of failure or crash.
3. Bugs, Errors, and Defects
- Functional testing involves assessing for functionality and features.
- If bugs or defects infiltrate the system, this is measuredly affected.
- The software is checked for these at every step under functional testing in the software development life cycle.
- However, there is no need to test for bugs, faults, or errors while testing the system for non-functional requirements.
- Non-functional testing can analyze the system’s behavior under several different conditions, the response time, and the user experience.
Functional Testing vs Non-Functional Testing Comparison Table
| Parameters | Functional Testing | Non-Functional Testing |
| Objective | Validate software actions | Validate the performance |
| Usage | Verifies the behavior of the application | Verifies the performance of the application |
| Execution | Carried out before non-functional testing | Carried out after non-functional testing |
| Requirement | Easy to define functional requirements | Difficult to define the requirements for non-functional testing |
| Focus Area | Client’s requirements | Client’s expectations |
| Manual Testing | Easy to execute | Difficult to execute |
| Requirements | Functional specifications | Performance specifications |
| Example Test Case | Check login functionality | Checking how many people can simultaneously login into the software |
| Functionality | Describe what the software does | Describe how the product works |
Functional vs Non-Functional Testing Examples
Examples of Functional Testing Types:-
- Interoperability
- Smoke Testing
- Globalization
- User Acceptance
- Unit Testing
- Regression Testing
- Integration Testing
- Localization
Examples of Non-functional Testing Types:-
- Performance Testing
- Portability Testing
- Compliance Testing
- Scalability
- Usability Testing
- Load Testing
- Stress Testing
- Volume Testing
- Disaster Recovery Testing
Final Thoughts
This article explores what functional and non-functional testing is. Looking at the comparison and differences between functional vs. non-functional testing, it becomes simple to understand that these are strikingly distinctive but equally important. There are different ways and strategies for performing both. It is essential to provide the requirements and specifications of the system and the client’s expectations beforehand to make it easy for the testers to conduct these tests. Before launching the software, it is necessary to examine whether it meets both functional and non-functional needs properly.
Frequently Asked Questions (FAQs)
1. What are functional and non-functional testing with examples?
Answer: Functional testing is a type of software testing that verifies whether an application meets its intended functional requirements. Examples: testing whether a login page allows a user to log in successfully or testing whether a search function returns accurate results.
Non-functional testing tests the application’s performance, reliability, and other non-functional requirements. Example: testing whether a website can handle high traffic, whether it is secure, and whether it is user-friendly.
2. What is the difference between functional and non-functional testing?
Answer: The main difference between functional and non-functional testing is that functional testing checks whether an application meets its intended functional requirements, while non-functional testing checks whether an application meets its non-functional requirements, such as performance, security, and usability.
3. What are the three functional tests?
Answer:
The three main types of functional testing are:
- Unit Test: Unit testing tests individual units of code.
- Integration Test: Integration testing tests the interaction between different units or components
- System Test: System testing tests the entire system.
4. What is the difference between functional and functionality testing?
Answer: Although functional testing and functionality testing are used synonymously, they are not the same. Functional testing verifies whether an application meets its intended functional requirements, while functionality testing tests whether an application meets its overall functional requirements, including both its intended and unintended features. In other words, functionality testing is broader than functional testing and may include testing for features that are not explicitly stated in the requirements.
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