Skip To Content
Back to Ponderings

Functional vs. Non-Functional Software Testing Types 

Types of Quality Assurance Testing Methods in Software Development

software testing types

Software testing is an integral part of software engineering. Bugs and errors are an unavoidable part of custom software development, making software testing critical to the performance and success of a software system. Also known as quality assurance (QA), software testing is the process of evaluating and verifying that a software product or application does what it is supposed to do. The benefits of testing include preventing bugs, reducing development costs, and improving performance. Software testing finds defects in software before it is released to the public or used in production.    

There are several different types of software testing methodologies that can be performed. Below is a breakdown of the different types of functional and non-functional QA testing techniques used in custom software development, along with some general best practices on where the different types of software testing are most appropriately applied.  

Functional Testing Types (with Examples) 

Functional testing is a type of black-box testing that bases its test cases on the specifications of the software component.  Functional testing verifies that a particular function or feature of a system works properly and is often included in regression testing. In functional testing, testers create test cases by describing a software component’s input and output conditions. They then execute these tests to verify that the component behaves as expected.   

There are several types of functional testing types in software testing, such as the following:  

Unit Testing 

Unit testing is a software verification and validation method in which a programmer tests if individual units of source code are fit for use. Developers write unit tests for their code to ensure the code works correctly. The development team primarily performs unit testing while modules are being created or reworked 

Integration Testing 

Integration testing involves testing a system as it is being developed. This type of testing is often used to test how well software components work together.    

Graphical User Interface (GUI) Testing 

Graphical User Interface (GUI) testing can be performed manually by visually verifying interface behavior or recording the actions performed on the interface into a test script. One common type of GUI testing is verifying that all interface elements are present and functioning as intended. This includes buttons, icons, text fields, and other elements. Another common task is verifying that input and output are correctly formatted and that the application responds as expected.    

Regression Testing 

Regression testing helps ensure that changes or updates made to the software do not impact any other functionality or processes. This testing type is one of the most critical aspects of software testing. It can be done manually, but it is often better to use regression software testing tools. These tools can automate the testing process, making it faster and more efficient.  

Sanity Testing 

Sanity testing is performed after receiving a software build with minor code changes or functionality to ascertain that the bugs have been fixed and that no further issues are introduced due to these changes. The goal is to determine that the proposed functionality works as expected. If the sanity test fails, the build is rejected to save the time and costs involved in more rigorous testing.   

Smoke Testing 

Smoke testing is a software testing technique performed post-software build to verify that the critical functionalities of the software are working. It is executed before any detailed functional or regression tests are conducted. The primary purpose of smoke testing is to reject a software application with defects so that the QA team does not waste time testing broken software applications.  

Negative Testing 

Negative testing is the process of testing a piece of software for defects. This checks the software application for unexpected input data and conditions. Negative testing aims to prevent the software application from crashing due to negative inputs and improve quality and stability.   

Happy Path Testing 

Happy path testing is a technique used in software testing to ensure that the most important and common use cases are checked thoroughly.  Happy path testing is not a replacement for other types of testing but should be used in conjunction. It is beneficial for regression testing as it is a quick and easy way to ensure that no new bugs have been introduced into the system.   

Exploratory Testing 

Exploratory testing is done without following a formalized plan or test design technique. It includes general software tests performed during the initial stages of development to assess the quality of the software. The purpose of exploratory testing is to find defects and problems in the software. It helps to identify what needs to be tested in more detail and can also help to prioritize which tests should be run first. Exploratory testing is often done by a tester familiar with the software and the system under test.  

User Acceptance Testing 

User acceptance testing is conducted to determine whether a system satisfies its acceptance criteria and to enable the client or user to decide whether to accept the system. The client usually performs acceptance testing, however other stakeholders or users may be involved as well. The goal of acceptance testing is to establish confidence in the system.  

API (Application Programming Interfaces) Testing 

API testing is a type of software testing that involves testing application programming Interfaces (APIs) directly and as part of integration testing to determine if they meet expectations for functionality, reliability, performance, and security.  

Black-Box Testing 

Black-box testing is a process of checking the functionality of an application as per the customer requirement. Black-box testing is often used to test applications already in use. It is a cost-effective way to ensure functionality has been maintained throughout an application’s life.   

White-Box Testing 

White-box testing is an approach that allows testers to inspect and verify the inner workings of a software system—its code, infrastructure, and integrations with external systems. The tester chooses inputs to exercise paths through the code and determines the appropriate outputs.   

Non-Functional Testing vs. Functional Testing 

Non-functional testing is an approach that verifies if the non-functional requirements remain satisfied. This is the opposite of functional testing, verifying all functional requirements remain satisfied.   

Non-functional testing is often used with functional testing to verify all system requirements are met. This testing can be done at any time during the software development life cycle but is usually performed near the end of the project when most of the system’s functionality is implemented.   

Non-Functional Testing Types (with Examples) 

There are several types of non-functional testing methods and techniques, such as the following:  

Load Testing 

Load testing puts pressure on a system or application to see how it responds. This type of testing is used to determine how well a system stands up to high traffic or other stress rates. Load testing should not be confused with performance testing, which measures how well a system performs under load. When developing a load test, it is essential to ensure that the parameters are realistic, and that the system does not crash or become unusable. This includes setting the number of users, the length of time for each test, and other factors. Several different commercial and open-source tools can be used for load testing. One popular tool is JMeter, which is used to test web applications. JMeter can simulate many users accessing a website or application simultaneously.  

Performance Testing 

The performance testing process tests the speed, response time, stability, reliability, scalability, and resource usage of a software application under a particular workload. The primary purpose of performance testing is to identify and eliminate the performance bottlenecks in the software application.   

Stress Testing 

Stress testing is used to check the accessibility and robustness of software beyond usual functional limits. The primary purpose of stress testing is to confirm that the software does not crash by the lack of resources like disk space, memory, etc.   

Compatibility Testing 

Compatibility testing is when users test the compatibility of an application or system with other software, hardware, or operating systems. This type of testing can identify and isolate compatibility issues before release.  

Limit Bugs with Comprehensive Software Testing Processes 

While the above isn’t a comprehensive list of every software test type, it contains the most common software testing methods that a quality assurance team may perform throughout the custom software development process. Building bug-free software is impossible, but consistently applying functional and non-functional tests to a software application can reduce errors and help make a software product a success with users. 

Be a Fly On the Wall Subscribe to our newsletter, Metamorphosis, and get a leap ahead of your competitors through guest contributed articles, white papers, and company news.

We don't support Internet Explorer

Please use Chrome, Safari, Firefox, or Edge to view this site.