Performance Testing Vs Functional Testing! Which One To Consider & Why?

Performance Testing Vs Functional Testing! Which One To Consider & Why?

James Wilson
March 29, 2022


First things first- What is Software testing and why does it matter?

Software testing checks all kinds of applications and programs to determine glitches that could induce troubles later, such as usability, data entry, processing issues, or anything else that could hinder users or compromise their data which is more gruesome.

These intricacies can be disastrous for businesses that profit by selling software. When a company loses its consumers' trust, it loses its revenue, loyalty, and commitment.

Such problems can also be highly challenging for businesses that use their custom-developed applications for their employees or internal operations. When a business fails its employees' trust, it fails its obligation to the company's mission. And when it loses crucial data, it loses productivity, efficiency, and the capacity to respond well to consumer requirements.

Any of these delinquencies can be challenging to bounce back from.

Functional Testing vs. Performance Testing, What is the value of using both?

Functional testing and performance testing processes are two types of software testing and quality assurance (QA) that entitle developers and performance engineers to guarantee the quality of their code. However, not all engineering teams execute testing when developing. This blog post will explain what functional and performance testing are, how they relate to each other, and when to choose one.

What is Functional Testing?

A functional test asserts that a piece of software is functional, which means that it yields the desired output for a given input. It evaluates a software system's unique and cohesive behavior functions to confirm that they adhere to pre-defined specifications. These tests work on a list of information and associated desired outcomes so that they can produce a definite "pass" or "fail" signal. It tests the functional precision, interoperability of subsystems, and adherence with pre-defined standards in the context of functional and business conditions. Functional tests are commonly used for reversal testing as they can quickly confirm that a shift in the performance did not break the overall software.

What is Performance Testing?

A performance test inspects whether a software stays functional with expanded demand and under various environmental requirements. It's more of a "functional test at scale", additional performance testing styles, such as load testing, soak testing, spike testing, and stress testing, specify the number of total users interacting with the software at a given time and define how this number changes over time. It is a non-functional testing technique that exerts a system, measures, validates, and confirms the response time, speed, reliability, stability, and scalability in a production-like environment.

It's not definitive for performance tests to result in a definite "pass" or "fail". The software might yield the correct output but need an inappropriate amount of time to do so. In performance testing, you can estimate your software based on various KPIs, including response times and error rates.

This table will highlight the differences more apparently to give a deeper understanding-

Functional testingPerformance testingTo verify the software accuracy with definite inputs against expected outputs.To verify the system behaviour at various load conditions.One user performs all level operations.Multiple users perform desired operations.It can be either manual or automated.It performs better when automated.Production sized test environment is not mandatory and H/W requirements are minimally.Mandated close to production test conditions & several H/W facilities to populate the load.Customers, developers, and testers' involvement is required.Involvement needed from Consumer, Tester, Developer, DBA, and N/W Management team.

Planning Tests in your Software Development Lifecycle: Which one should you choose?

In the early stages of software testing and development, functional tests often take the first seat and performance tests. With some development methodologies, such as TDD (test-driven development), developers create functional tests even before implementing the feature being tested.

Putting functional tests at the beginning makes sense because why would you either way run performance testing on something that doesn't work.

However, performance testing should also be on your mind, given your customers expect better performance from you and they've experienced your competitor's software performances already.

Additionally, it's a poor notion to run performance tests only after receiving negative feedback only. You should solely avoid any such ideology. Include these tests when you’re planning your project and start building them once you have completed your first performance-critical features, their functional tests, and their production infrastructure.

Author Bio:

James Wilson is a seasoned Content Writer at Net Solutions, New York, for ten years with an expertise in blogging, writing creative and technical copy for direct response markets, and B2B and B2C industries. Born and brought up in New York, James holds a bachelor’s degree in English Literature. He has worked for industries like IT, software product design and development, Lifestyle, and written some great insights on technologies like user experience design, mobile app development, eCommerce, etc. Besides his technical background, he is not very disconnected from the digital in his free time – he loves to binge-watch Netflix.


Publish your blog on this space.

RedAlkemi publishes a collection of blogs submitted by guest bloggers in the space of digital marketing, graphic design and web development. If you think you can add value to our blog with your content, we'd love to have you on board! Email us at