What Is Non-Functional Testing? (Plus 11 Common Types)

By Indeed Editorial Team

Published May 28, 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Software testing is helpful in determining if products are defect-free and perform as expected. They're necessary as guideline checks for various stages after building the product but before the product launch. Understanding non-functional testing can aid your career in software or product development. In this article, we discuss what non-functional tests are and identify the various types.

What is non-functional testing?

Non-functional testing is the type of software testing that examines non-functional parameters of the software, such as the software's ability to work in an external environment. These non-functional parameters are reliability, performance, load testing, and accountability of the software system. This type of testing entails executing software components using manual or automated methods to evaluate one or more of the properties of interest to uncover mistakes, gaps, or missing requirements compared to fundamental requirements.

This testing process defines the method for software setup, installation, and execution. This involves producing and collating sufficient metrics and measurements for internal research and development. It also gives detailed knowledge of the product behaviour and reduces the risk of launching defective products and the associated costs that come with it.

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Types of non-functional tests

Here are common types of non-functional tests:

1. Performance testing

Performance testing determines how well software components function. These tests identify flaws in software design and architecture performance. The testing accomplishes this by measuring software response time, detecting bottlenecks, and identifying failure points. It eliminates the cause of the software's slow and limited performance. This testing measures the reading speed of the software, ensuring that it's set to be as fast as necessary. Performance testing requires a well-structured and explicit statement of expected speed, otherwise, the test's outcome (success or failure) is ambiguous. This ensures software quality by confirming fastness, scalability, stability, and dependability. Examples of performance testing include:

  • When 10,000 people use the website simultaneously, ensure that the response time isn't longer than five seconds.

  • When network connectivity is slow, ensure that the response time of the application under load is within an allowable threshold.

  • Examine the maximum number of users that the software can support before crashing.

2. Load testing

Load testing examines how the software performs under regular and peak workloads. This determines how much work the software can manage before performance declines. Load tests involve running numerous applications concurrently, subjecting a server to a high volume of traffic, or downloading a large number of files. Load testing guarantees that software is both quick and scalable. Some typical load testing examples may include testing a printer by transmitting a considerable number of documents for printing or testing a mail service with thousands of concurrent users.

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3. Security testing

Security testing works by helping to identify software application security issues. The testing happens by analyzing system architecture while assuming an attacker's attitude. Test cases occur by locating portions of code where a cyberattack is most likely to occur to demonstrate the application's security. Typical security testing examples include:

  • Scanning for vulnerabilities

  • Testing for penetration

  • Risk evaluation

  • Audits of security

  • Assessment of posture

  • Ethical hacking

4. Reliability testing

Reliability testing determines whether the software can conduct a failure-free operation in a specific environment for a specified period. The reliability test fails if the software doesn't perform as expected under any of these processes. The objectives of reliability testing are to find the structure of recurrent breakdowns and measure the number of failures that occur in a certain amount of time. It also involves determining the software's mean existence and identifying the key driver that's the source of the failure. For example, whether the software can withstand high user traffic and requests for several hours without crashing.

5. Recovery testing

Recovery testing validates software's capacity to recover from failures, such as software-hardware disasters and network outages. The goal of recovery testing is to establish whether software operations can resume following a crisis or integrity loss. Recovery testing entails returning software to a known state of integrity and reprocessing operations up to the failure point. The number of restart points, the volume of applications, the training and skills of those performing recovery activities, and the accessible recovery tools determine the time it takes to recover.

When multiple failures occur, there are systematic attempts at recovery testing instead of addressing them together. This means performing recovery testing for one segment before moving on to the next. An example of recovery testing is to restart the computer abruptly while an application is running and check its data integrity or unplug the connecting cable while an application is getting data from a network.

6. Usability testing

Usability testing, often known as user experience (UX) testing, determines how user-friendly a software product is. A small group of intended end-users uses the software to expose its usability flaws. Usability testing primarily focuses on how easy it is for users to navigate and interact with the application, its control flexibility, and how effectively it can achieve its set objectives. The optimal time for this testing is during the early design phase because it provides more insight into the consumers' expectations. Usability testing follows the following steps:

  1. Planning

  2. Recruiting testers

  3. Usability testing

  4. Data analysis

  5. Reporting

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7. Interoperability testing

Interoperability testing is a sort of software testing that determines whether a program can connect with other software components and systems. Interoperability tests guarantee that the software product can communicate with other components or devices without compatibility difficulties. Precisely, interoperability testing entails demonstrating that end-to-end functionality between two communicating systems meets the requirements. Usually, a lack of such testing can lead to data erasure, inconsistent performance, untrustworthy operations, incorrect operation, and poor maintainability. An example of interoperability testing can follow this path:

  1. Connecting multiple devices from different vendors

  2. Checking the connectivity between devices

  3. Checking if devices can send or receive packets or frames from each other

  4. Checking if data handling is correct in the network and facility layers

  5. Checking if implemented algorithms work correctly

  6. If the result is ok, check the next result

  7. If the result is not ok, use monitor tools to detect the source of the error

  8. Reporting results in the test reporting tool

8. Portability testing

Portability testing ensures that, when installing the software on a new system or platform, it continues to function as expected. This means there's no loss of functionality due to a change in the environment. During testing, it's also necessary to test the difference between multiple hardware configurations, such as hard drive space, processor, and operating systems. The goal is to ensure the application's desired behaviour, and expected functionality always remains intact. Examples include creating software for various operating systems or creating an application for any common operating system.

9. Volume testing

Volume testing determines system performance when the database experiences a surge in the amount of data it contains. It's also referred to as flood testing. This determines what difficulties can arise as data volumes increase. Volume tests determine data loss, warning or error messages, or data storage concerns. They also ensure that systems respond to specific data volumes as intended. This is necessary to ensure performance and stability.

For example, when volume testing an application with a specified database size, expand your database to that size by adding more data to the database to increase capacity and run the test. This examines the volume at which a system's stability begins to deteriorate. It also examines the system's response time, if data becomes overwritten without notification, and whether data storage is proper.

10. Stress testing

Stress testing examines how the software performs under unusual conditions. Stress tests let you discover the upper limits of a system's capability by applying a greater load than the projected maximum, which is the point at which the software fails. It's critical to understand what happens when stress happens in the system. Is the correct error message displayed? Is the system broken? How can it recover? Stress testing also investigates what occurs when a system fails. This assures that the program is recoverable, stable, and trustworthy.

A popular example of stress testing is an education board's website. When an institution releases its results, the website is likely to experience a spike in web traffic. This peak load occurs for a short period during the display of results. As a result, stress testing can assist in locating the application's breakpoint and examining the application's behaviour and recoverability in the event of a crash.

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11. Benchmark testing

Benchmark testing serves as the foundation for subsequent tests, comparing the performance of a new or unknown application to an established standard of reference. Benchmark testing involves analyzing an application's relative performance by checking if the application performs below the specified baseline. This test runs with each build, and a comparison of all critical attributes occurs to assist in problem-solving. For example, in the first iteration, an application's response time was five seconds. This forms the benchmark for subsequent iterations, so if they exceed five seconds, the software fails the benchmark test.

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