Your Guide to Functional vs. Non-Functional Testing

When creating an application, whether for banking, healthcare, retail, telecom, automotive, or another industry—there are a variety of tests that must be performed prior to releasing the application. A comprehensive test strategy is needed that will test your app in all areas—from functionality to performance to responsiveness under load, and more. These tests are often grouped into two main categories: functional and non-functional testing. 

But what are the differences between functional and non-functional testing? Are they both necessary?

In this blog, we will compare functional and non-functional testing to help you understand the differences and similarities between them, as well as their overlapping purposes. Incorporating both functional and non-functional testing into your testing strategy will put you well on your way to achieving complete continuous testing. 

Related Reading: Test Coverage Guide

What is Functional vs. Non-Functional Testing?

Functional testing is a series of tests that determine an application’s capabilities related to its intended primary functions. Non-functional testing checks the features of an application that are not critical to the app's main function but are still important for user experience. 

Functional Testing Overview

Functional testing assesses whether the primary functions of a software application are working and that they align with the overarching goals for the app. Functional tests result in ‘pass’ or ‘fail’ scenarios because the features either work as designed or they do not. 

Functional testing determines whether an application, website, or program is operating exactly as designed. Some examples of questions that functional tests pose might include:

• Does a banking app allow a user to login after they enter their credentials?
• Does the payment system on an eCommerce site prompt an error message after the user enters an incorrect credit card number?
• When a user clicks ‘Buy Now’, does the application take them directly to the checkout page?
• If a user enters characters into a field where they are not allowed, does the application stop functioning?

As you can see, functional testing tests to see if the most crucial components of an application are working properly. 

Related Reading: What Is Functional Testing?

Types of Functional Testing

Now that we have covered the purpose of functional testing, let us look at some of the different types of functional testing: 

Unit Testing

Unit testing is the process of testing the smallest component of code. With unit testing, testing teams test each individual code block to ensure its accuracy prior to adding it to the largest codebase. Unit testing paves the way for the other forms of functional testing by ensuring the underlying code is accurate and functional. 

Component Testing

Component testing, also known as module testing, is the process of testing and evaluating individual components of an application. This testing approach focuses on the performance of an app with the goal of detecting any bugs or glitches in functionality, rather than focusing on the code (as with unit testing). Typically, component testing takes place after the code has been tested during the unit testing phase. 

Integration Testing

After component testing has been performed, testing teams must integrate the separate components of the application. This is where integration testing comes into play—to test the overall functionality of the app when all components are working in tandem. 

End-to-End Testing

End-to-end testing, also known as system testing, tests an application’s flow from beginning to end. The purpose of end-to-end testing is to simulate real-user scenarios to ensure that your application is running smoothly from end to end. 

Regression Testing

Regression testing tests your application every time there are updates to the existing software or a change in the underlying code. The goal of regression testing is to ensure that your application continues to perform smoothly as platforms, OSs, code, and browsers are updated—without any gaps in service. 

Sanity Testing

Like regression testing, sanity testing checks for the stability of an application after changes have been made. However, sanity testing focuses specifically on testing changes to code, rather than the overall functionality of the application. 

Smoke Testing

Smoke testing is the last type of testing to take place after an app is completed. Smoke testing checks to see if there are any components of the app that need further testing prior to release. It serves as a checkpoint to ensure the application can be released with confidence. 

Non-Functional Testing Overview

Non-functional testing tests for aspects of an application that are not central to its function. Some examples of non-functional elements include performance, usability, stability, efficiency, and more. These examples of non-functional testing help ensure that the application has a smooth user experience. Functional and non-functional testing are both necessary for the overall success of an application. 

The following are some of the uses of non-functional testing:

• Identify gaps in the effectiveness and stability of an application.
• Reduce the risk of bugs and glitches—and in turn, reduce the risk of poor user experience or financial losses.
• Simplify the maintenance of the application.
• Identify the metrics needed to track the application’s success (based on real user feedback).

While non-functional testing does not test the primary aspects of an app’s functionality like functional testing does, it is nevertheless crucial to the overall success of an application. Both functional and non-functional testing are needed to ensure an application is working as intended. 

Related Reading: What Is Non-Functional Testing?

Types of Non-Functional Testing

Now we will take a closer look at types of non-functional testing:

Performance Testing

Performance testing is a type of non-functional testing that tests the application under a variety of capacities to ensure that it is running at optimal performance. Some capacities tested during performance testing include loading speed, crash rate, memory, speed, stability, reliability, responsiveness, and resource usage. 

Load Testing

Load testing determines how well an application functions under heavy load and peak traffic events, such as Black Friday, or other instances in which many people are using your app at the same time. 

Related Reading: Navigating the Black Friday Blitz

Security Testing

Security testing tests an application from the vantage point of a would-be hacker to uncover vulnerabilities. A security test scans the app to see instances where data can be taken, where unauthorized changes can be made to the app, etc. 

Reliability Testing

Reliability testing tests to make sure an application functions in all areas without bugs, particularly during challenging real user conditions.

Efficiency Testing

Efficiency tests check to see the volume of resources used for the app to accomplish its function. 

UX Testing

UX testing is the process of obtaining feedback from real users to determine how they experience and interact with an application. The purpose of UX testing is to improve the overall quality of your application to maximize customer satisfaction, and therefore reputation. 

API Testing

API testing evaluates an application’s interface to ensure it meets functionality, security, and performance standards. 

Accessibility Testing

Accessibility testing ensures that your application is usable to as many people as possible, including those with differing vision, hearing, physical, or cognitive abilities. Not only is accessibility testing the right thing to do—it also ensures compliance with laws and regulations.  

Related Viewing: Accelerate Accessibility With Perfecto

Functional and Non-Functional Testing With Perfecto & BlazeMeter

Functional and non-functional testing has never been easier with the combined power of Perfecto and BlazeMeter. As part of Perforce’s Continuous Testing suite, Perfecto and BlazeMeter allow you to shift both functional and non-functional testing left under one umbrella. By incorporating both types of testing earlier in the software development lifecycle, you have newfound opportunities to make your testing more comprehensive and mitigate risks that come with escaped defects.

When you partner with Perfecto and BlazeMeter, your team will be able to maximize your continuous testing and shift quality left. In addition, you will:

• Create, execute, and analyze all testing types: API, Functional, Non-Functional, Exploratory, Unit, all at maximum scale. 
• Get a clear view of your entire mobile experience. Test on thousands of devices, OSs, and browsers across the globe and see how your mobile app performs in real-world conditions. 
• Prepare for peak traffic times like Gap, BT, and the New York Times. Scale up to over 2M virtual users during performance testing.  
• Live test your apps for web & mobile as if you were a real user, down to the very swipe/click and even with image injection, biometric testing, location, accessibility testing, network virtualization, and more.  
• Test your native mobile Android and iOS binary applications manually and automatically. 

Related Reading: Achieving Continuous Testing With Perfecto & BlazeMeter

Bottom Line

Perfecto and BlazeMeter are your go-to partners for achieving complete continuous testing. Together, you will be able to perform functional and non-functional testing at scale and release high-quality applications that succeed on the global marketplace. 

Get started with functional and non-functional testing and more by requesting a custom demo of Perfecto and BlazeMeter.

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