What are non-functional tests?: Types, tools and processes

It is essential to deliver fully functional software. But non-functional system requirements are equally important.

A critical step in software testing and quality assurance, non-functional testing evaluates a system's attributes in addition to functional requirements. This type of testing focuses on evaluating qualities such as usability, reliability, security, and performance for areas of improvement before production.

Definition of non-functional tests

Non-functional testing is the process of evaluating the operational aspects of a software system rather than focusing on its specific functionalities. It involves evaluating the operational characteristics of the system, with a focus on studying how a system functions under stress.

A non-functional test aims to evaluate crucial factors that can significantly impact user satisfaction levels and system reliability. Many development teams use non-functional testing to determine whether a project is ready to go into production. By verifying software resilience and effectiveness under real-world conditions, teams uncover potential issues that may have gone unnoticed during functional testing. Ultimately, this allows them to provide higher quality software.

Main Aspects Evaluated

Non-functional testing focuses on evaluating software system attributes that influence performance and usability, rather than specific functionalities or behaviors. Ensures systems meet qualitative aspects of user requirements and operating environments.

For example, scalability testing checks an application's ability to handle fluctuations in user demands. Compatibility testing evaluates the app across multiple platforms and devices. Security tests evaluate data protection features and mechanisms. Encompassing a wide range of testing types, non-functional testing ensures teams release software that is easy to use, robust, and reliable in a variety of conditions.

Types of non-functional tests

Non-functional testing focuses on qualities such as compatibility, availability, and disaster recovery testing techniques. It also covers various testing approaches.

Performance test

Performance tests evaluate the stability and efficiency of software under different conditions. Some of the main performance testing categories include:

• Load testing evaluates the behavior of a system under expected user loads.
• Stress testing helps teams determine the breaking point of software, pushing it beyond normal operational capacity.
• Endurance testing verifies the long-term stability and consistent performance of the system by subjecting it to extended operations.

Testing usability

Usability testing checks and evaluates an application's ease of use to ensure it is intuitive and accessible to end users. One of the most common usability testing methods is A/B testing, which involves comparing two versions of a user interface to determine the best-performing option. Heuristic evaluations, another popular method, involve evaluating software against established usability principles to find areas for improvement.

Scalability Test

The purpose of scalability testing is to determine whether an application can be scaled up or down to accommodate fluctuating levels of demand. It ensures that as the data volume or number of users increases, the software can handle the additional load without degradations in performance levels. This ensures that the software has the ability to handle continuous growth while remaining functional, stable, and responsive under diverse conditions.

Security Test

Security testing involves using various techniques to ensure that an application has robust data protection. This helps protect the system against data breaches and cyber attacks.

Security testing techniques include:

• Vulnerability scanning: Security weaknesses identified.
• Penetration testing: Simulates attacks to assess a system's defenses.

Security testing protects software against unauthorized access to user data and information, ensuring confidentiality and integrity.

Reliability and availability testing

Reliability and availability tests verify that the software operates without interruptions, maintaining high uptime and resilience to failures. These tests confirm proper functioning over time and under varying conditions, helping maintain user confidence in the application and ensuring reliability.

Compatibility Test

In compatibility testing, development teams test software functionality across different operating systems, devices, and browsers. This verifies that the software is hardware independent and remains easy to use and effective under various operating conditions. Compatibility testing helps create a consistent user experience across different hardware and software systems.

Disaster Recovery Testing

This type of testing evaluates a system's ability to recover from disasters or catastrophic failures. By simulating various disaster scenarios, testers verify that planned recovery procedures are effective. They also evaluate how quickly data can be restored to minimize downtime and protect critical business functions.

Tools for non-functional testing

Development teams have many tool options for each type of non-functional testing.

Tools for performance testing

The tools help evaluate how well an application or software handles stress and high loads based on performance metrics. JMeter is one of the most popular tools for this task. It is an open-source and highly customizable tool for testing web applications. NeoLad is a favorite tool for testing the performance of web and mobile applications under high demand, with fast and accurate results in agile development environments. LoadRunner is a favorite due to its ability to simulate thousands of concurrent users.

Tools for security testing

Security testing tools assist testers in identifying vulnerabilities in their software. OWASP ZAP is the right choice for scanning web applications to reveal security issues. Wireshark assists in analyzing network protocols to gain insights into areas of an application with potential for breach through active network monitoring. Nessus prioritizes security risks after scanning for vulnerabilities and offers extensive configuration options for enhanced customization.

Tools for usability testing

Usability testing tools help optimize the user experience and system interface. Crazy Egg, for example, offers heatmaps and visitor insights to help teams better understand user engagement. Many teams use Hotjar in their applications to collect session recordings, data, and user interactions to realize necessary usability improvements. Meanwhile, Optimizely is a great option for determining the best-performing options or elements through A/B testing.

Importance of non-functional testing in SDLC

Testing the non-functional aspects of software is a vital part of the software development lifecycle. By focusing on the broader aspects of the software, these tests help teams ensure their final products are as robust, secure, and easy to use as they are functional. Identifying and addressing potentially problem areas early in the SDLC reduces the risks of failure while also leading to higher user satisfaction and retention rates.

Non-functional testing process

Non-functional testing follows a cyclical pattern, similar to other types of testing.

#1 Requirements Analysis

Non-functional testing begins with determining the non-functional aspects and requirements of the software to be analyzed. The goal of this step is to understand user expectations regarding usability, performance, security, and other non-functional qualities.

This initial phase involves gathering and refining these requirements with stakeholders. It also includes prioritizing non-functional requirements and determining necessary standards and benchmarks. For example, teams creating a banking app may want to prioritize security over aesthetic elements to protect user data.

#2 Planning and Design

The test plan and design phase involves selecting the appropriate tools and techniques for the specific software being tested. For example, teams employ JMeter for testing application performance and Nessus for vulnerability testing. Creating a test environment as a replication of the real production environment is a crucial aspect of the process. This ensures test results are accurate and reflect real-world conditions to help teams understand application performance in typical scenarios.

#3 Test Execution

After finalizing the projects, the teams execute test plans to evaluate the non-functional aspects of the software. This includes security checks, usability assessments, and load testing. Testers observe and monitor the behavior of the software and tools selected for testing to collect the most detailed data possible. This information provides highly valuable insights to help teams optimize software, such as areas causing performance bottlenecks and security vulnerabilities.

#4 Results analysis

After completing all required non-functional testing, testers compile data from each source (including the tests themselves and results from various tools) to construct a detailed report. This comprehensive report of the software's non-functional performance should include a comparative analysis of results against predefined benchmarks and standards. When building it, testers provide development teams and stakeholders with a list of areas and components that require adjustments or optimization.

#5: Reporting and Feedback

Using the data compiled in the previous step, testers create a comprehensive report on findings from non-functional tests. This report includes highlights of the app's strengths and areas for improvement. Data must be structured in a clear, actionable and prioritized way to outline next steps. Testers then send the report to developers to establish a feedback loop and ensure immediate action.

#6 Optimization and retesting

Developers then implement the necessary changes based on test results and feedback. After completing modifications, testers retest the software to ensure that all problem areas have been resolved and that no new problems have been introduced.

Best Practices

Following best practices for non-functional testing better ensures that teams produce the highest quality software possible.

Clear Definition of Objectives

• Setting clear benchmarks : Teams should define measurable benchmarks for each non-functional test area before beginning. An example of a benchmark could be determining that a website should take no more than five seconds to load.
• Understanding user expectations : Active engagement with stakeholders and end users facilitates a better understanding of software expectations. This information allows the team to create more accurate real-world usage scenarios and understand user needs.

Realistic test environments

• Mimicking production : The testing environment should closely reflect or imitate the production configuration. Discrepancies between the two environments can result in misleading test results.
• Frequent environmental assessments : Teams should regularly review and update the test environment to incorporate changes made in production, such as hardware modifications and software updates.

Comprehensive test coverage

• Cover all non-functional aspects : Testers should not just focus on a single aspect of non-functional testing. Instead, they should aim to cover all relevant non-functional areas crucial to a holistic testing approach.
• Use varied test scenarios : Tests should be designed to cover best-case to worst-case scenarios. This more accurately assesses the responsiveness and adaptability of the software.

Continuous Monitoring

• Utilize monitoring tools : Real-time monitoring tools for testing empower teams to identify and resolve issues immediately, preventing bottlenecks, vulnerabilities, and other issues. These tools also help ensure that software meets various security and performance standards under different conditions.

Regular reviews and updates

• Periodic Test Review : Non-functional requirements evolve along with the software. To keep up with new releases and current needs, teams must regularly review and update benchmarks and test scenarios.
• Staying up to date on testing trends : As non-functional testing continually advances, it's important for development teams to stay up to date on new tools, techniques, and best practices. This keeps tests (and testers) effective and efficient.

Collaboration and Communication

• Involve all relevant teams : The non-functional testing process should include testers, developers, system administrators, stakeholders, project managers, and end users. These diverse perspectives provide broader insights and enable teams to design better tests.
• Promote open communication : Teams must establish a supportive environment with open feedback, suggestions, and discoveries for more innovative solutions through collective problem solving.

Conclusion

Non-functional testing is an important complement to functional testing. By focusing on the operational aspects of software, non-functional testing plays a crucial role in evaluating areas of the application that impact the user experience. These tests ensure that your software is not only technically sound, but also easy to use and capable of handling a variety of use cases. Non-functional testing is a critical step in delivering high-quality, comprehensive software that meets relevant standards and exceeds user expectations.

Common questions

What differentiates non-functional from functional tests?

Functional testing verifies that specific software functionalities work as intended. Non-functional testing involves evaluating broader attributes of a system, such as security, usability, scalability, and performance.

How often should non-functional testing be performed?

Teams should perform non-functional testing regularly, especially after updates and feedback cycles. They must continuously test in CI/CD environments. It is also important to perform specific assessments of applicable milestones when necessary, such as in the case of a new feature release.

How does non-functional testing differ from integration testing?

Integration tests verify that components are interacting correctly, while non-functional tests ensure that integrated systems meet broader standards, including performance and reliability. Both testing procedures are essential for creating robust software systems.