Software Functional Testing A Complete Guide

To achieve a bug-free product, your QA team must carry out both functional and non-functional testing. While non-functional testing often takes center stage to ensure usability and performance, it’s easy to overlook functional testing, where many defects may lurk. However, with the right understanding of its value, functional testing can become an integral part of your development cycle.

But what exactly is functional software testing? Which tools support functional testing? And how can you execute functional tests effectively?

This comprehensive guide answers these questions and more, offering a breakdown of functional testing, how to test software functionality, and which tools can help optimize the process.

What Is Functional Software Testing?

Functional software testing focuses on verifying that a software product meets the functional requirements and specifications outlined by the development team. The goal is to test each feature of the product to ensure it works as expected when the appropriate input is provided, and the output is validated against predefined functional requirements.

In simple terms, functionality refers to what a product can do for the user. During functional testing, QA engineers run test cases to confirm that the software’s intended functionality aligns with user expectations. This includes testing the User Interface (UI), APIs, databases, security features, client/server communication, and other key functional aspects.

It’s important to distinguish functional testing from non-functional testing. While non-functional testing focuses on performance, usability, and reliability, functional testing centers on how the system behaves and whether it executes specific actions correctly. For example, functional testing ensures that a “submit” button works properly, while non-functional testing might assess how quickly the button can be clicked under heavy load.

How to Test Software Functionality

Now that you understand the concept of functional testing, here’s a look at how to conduct it. QA teams typically follow these five steps when performing functional tests:

1. Confirm the Software Requirements: Understand and review the functional requirements of the software.

2. Identify Test Input: Define the test data to be used for validating functionality.

3. Measure Expected Outcomes: Set up expected results for the test input values.

4. Perform Test Cases: Execute the test cases based on predefined scenarios.

5. Compare Results: Compare the actual results against the expected outcomes to verify functionality.

Types of Functional Tests

A strong QA process includes multiple types of functional tests to ensure a comprehensive evaluation of the product's behavior. Here are the key types of functional testing:

• Unit Testing: Ensures each individual unit or component of the software functions correctly.

• Regression Testing: Validates that existing features continue to work as expected after new code is added or changes are made.

• Integration Testing: Verifies that different software modules function properly when integrated into the system.

• Smoke Testing: Confirms that the software remains stable after a build is deployed.

• Sanity Testing: Ensures that the major and critical functions of the software work correctly after smoke testing.

Functional Testing Tool Specifications

To carry out functional testing effectively, your team will need the right functional testing tools. These tools help streamline the process, improve testing accuracy, and reduce the chances of human error. When choosing a tool, consider the following factors:

• Ease of Use: Is the tool user-friendly for all QA team members?

• Compatibility: Can the tool operate seamlessly across different platforms or environments?

• Customization: Does the tool offer features tailored to your team's specific needs?

• Reusability: Can test cases be reused to improve efficiency in future testing cycles?

Top Functional Testing Tools

While it's possible to perform functional testing without dedicated tools, using testing software can significantly reduce testing cycles, increase accuracy, and minimize errors. Here are some of the best functional testing tools for your team to consider:

• Selenium: An open-source, free tool that supports multiple programming languages like Java, Python, and C#. Selenium works across Windows, Mac, and Linux and is widely used for web application testing.

• Tricentis: Known for its model-based approach, Tricentis is a powerful end-to-end testing tool that supports both manual and automated tests. It’s particularly effective in Agile development cycles, where speed and efficiency are crucial.

• TestComplete: A versatile testing tool that supports testing across web, desktop, and mobile platforms. TestComplete can execute test cases in different languages and integrates with various defect tracking tools like Jira, Bugzilla, and Visual Studio.

• UFT (Unified Functional Testing): Developed by Micro Focus, UFT supports both functional and regression testing. It uses Visual Basic scripting for automation and allows you to combine manual and automated testing scripts within a single integrated environment.

• Watir: An open-source tool (free) that’s particularly useful for web application testing. Watir supports various browsers and emphasizes making test scripts easy to read, maintain, and understand, even for those with minimal coding experience.

What’s Next?

Now that you have a solid understanding of what functional software testing is and how to execute it, you may face more complex challenges. For instance, how do you carry out functional testing when resources or time are limited?

The answer lies in adopting the right tools, practices, and strategies to ensure functional testing becomes a seamless part of your development lifecycle. Incorporating automated testing, establishing efficient test planning, and continuously evaluating your testing processes will set your team up for success, leading to fewer bugs and a higher-quality product.

By investing in functional testing and leveraging the right tools, your QA team will ensure the functionality of your software is reliable, efficient, and up to customer expectations.