When people refer to "testing" in a general context, they often have functional testing in mind. It's about making sure that the core functions are working as they should.
Functional testing is a type of testing to check if features are working as expected according to its requirements. These requirements are either collected from the users or provided by the stakeholders (development team or product owner).
The primary goal of functional testing is to ensure that the software performs the functions it was assigned to do. Functional testing is one of the most common and foundational types of testing.
Here are some of examples of functional test cases on a Login page:
Read More: 100 Test Cases For The Login Page
Non-functional testing is a type of software testing that focuses on evaluating the non-functional aspects of the system, such as:
When doing functional testing, testers try to answer the question Can the system do what it was built to do?
When doing non-functional testing, testers try to answer the question Can the system do what it was built to do well enough?
Here are 4 examples of non-functional test cases:
Here is a simple comparison table for the differences between functional testing and non-functional testing:
|
Aspect |
Functional Testing |
Non-Functional Testing |
|
Purpose |
To verify if the software functions as intended and meets functional requirements. |
To evaluate non-functional attributes like performance, security, usability, and more. |
|
Focus |
Tests what the software should do. |
Tests how well the software performs certain functions or behaves under specific conditions. |
|
Scope |
Typically focuses on specific features or functionalities. |
Covers a broader range of attributes beyond functionality. |
|
Examples of Testing Types |
Unit Testing, Integration Testing, System Testing, User Acceptance Testing. |
Performance Testing, Security Testing, Usability Testing, Compatibility Testing. |
|
User Focus |
Ensures that the software meets user needs and expectations in terms of features. |
Ensures that the software meets user needs and expectations in terms of performance, security, usability, etc. |
|
Objective Measurement |
Often involves binary outcomes (pass/fail) based on expected behavior. |
Often involves quantitative measurements and benchmarks for non-functional attributes. |
|
Tools and Technologies |
Functional testing tools may include Selenium, JUnit, TestNG, etc. |
Non-functional testing tools may include JMeter, OWASP ZAP, L oadRunner, etc. |
Functional testing extends from component-level testing all the way to regression testing of existing features. It finds itself in any type of testing involved with functionality. If you are doing regression testing for a certain feature, that is still functional testing.
Let’s look at some popular testing types:
Functional testing starts with requirements, which are based on user stories.
A user story describes what a user wants and why. It usually follows this format:
For example:
"As a customer, I want to view my order history online so that I can track my purchases."
This story is a starting point, but it’s not detailed enough for development or testing. Testers must collaborate with users to understand their needs and put the story into a real-world context. By doing so, the story becomes a requirement, which guides development and functional testing.
User stories can be too broad. To make them actionable:
Once you have a clear test scenario, the next step is to write test cases. A test case is a set of conditions that testers use to verify whether a feature works as expected.
Each test case should include:
Read More: How To Write Test Cases? A Detailed Actionable Guide
After writing test cases, testers run them to verify functionality. Execution can be:
When running tests:
If a test fails, report it to developers with:
Read More: How To Create a Test Report?
Functional testing plays a crucial role and is tied to many other activities in the software development life cycle. However, teams usually use a number of fragmented tools that solve separate testing needs, which creates a collection of complex, brittle, and hard-to-scale tool-stacks for quality management.
This means you have 3 options to do functional testing:
Option 1: Build Your Own Testing Framework with Open-Source Libraries
Option 2: Single-Point Commercial Automation Testing Tools
Option 3: All-in-one software testing solution
Here's a list of good functional testing tools for your team
Now that you have broken down the user stories into small slices, let's see how you can automate them.
To start, you can download Katalon. In Katalon alone, you can do test planning, write tests, manage them in suites, schedule for execution across environments, and generate test summary reports. This comprehensiveness allows for a lot of customization and flexibility, no matter how complex the application under test is.
Download Katalon and Give It A Try
Once you have downloaded and installed Katalon, navigate to File > New > Project. You can choose the type of testing for this project, either web, API, mobile, or desktop app.
You have up to 3 modes of test creation:
Interested? Have a look at the demo here:
Moreover, Katalon sets itself apart by incorporating cutting-edge, native AI features to enhance functional testing. Users can autonomously generate test scripts from plain language input or use the "Explain Code" feature to add comments to code snippets for better understanding among stakeholders and team members. Check out our pioneering AI features here.
Do your team need a better solution for functional testing? Start now with Katalon Studio.
Download Katalon and start functional testing for free
Functional testing checks whether an application performs as expected based on defined requirements (e.g., verifying a login process). Non-functional testing, on the other hand, evaluates aspects like performance, scalability, usability, and security that are not directly related to functionality.
The requirements document serves as the foundation for functional testing. It defines what the application is supposed to do, helping testers create relevant test cases and ensuring that the application meets business needs.
Features are prioritized based on business impact, user frequency, and risk. Critical features like login, payment processing, or data submission typically take precedence over less essential functionalities.
Yes, functional testing often includes API testing to validate that APIs perform expected actions, return correct responses, and handle errors gracefully. Tools like Postman or REST-assured are commonly used for this purpose.
Functional testing includes edge cases by designing test scenarios that push the application to its limits (e.g., entering the maximum number of characters in a field). These tests ensure that the application handles unexpected inputs or conditions correctly.
Functional testing verifies whether specific features work as intended, often for new or updated functionality. Regression testing checks that existing features still work after changes, ensuring no new bugs are introduced.
Functional testing can be both manual and automated. Manual testing is used for exploratory or ad-hoc testing, while automation is preferred for repetitive test cases to improve efficiency and consistency.
Test data plays a crucial role in functional testing. It’s used to simulate real-world scenarios, validate inputs and outputs, and ensure the application behaves correctly under various conditions, including valid, invalid, and boundary inputs.