The Ultimate Guide To Functional And Non Functional Testing

The Ultimate Guide To Functional And Non Functional Testing

For a software developer, it is of utmost importance to maintain a seamless user experience. This is where software testing comes into the picture, which helps the developer identify and isolate bugs or issues with code. Two main types of testing are functional and non functional testing. These two distinct but interconnected testing methodologies are the baseline upon which software applications' reliability, efficiency, and user satisfaction are built.

In this particular blog, we will go through the world of functional and non functional testing. The main content that we will cover here in this blog piece are definitions, differences, and importance testing. Whether you are a developer, tester, or QA professional, understanding these testing methodologies will equip you to create top-grade software that aligns with user expectations.

So, let us take a look at both functional and non functional testing one by one.

What is functional testing?

Functional testing is a stage in which developers verify whether the application under the test’s features behaves as per their requirements. Functional testing is also called black-box testing. The developer has to test only the program rather than the whole system. It is the most important phase in software development because it helps identify errors from expected behavior before the software is released for public use.

The following are the key aspects to be kept in mind by a developer while running functional testing in software testing:
• Unit Testing: It deals with testing individual units or segments of the software to check if they function appropriately.
• Integration Testing: As the word ‘integration’ suggests, it ensures that multiple units or modules are working together as expected.
• Regression Testing: This ensures existing codes are running along with new changes and updates.
• User Acceptance Testing: It is done to see if the software meets the user's expectations and can be deployed.
• User Testing: This is a kind of real testing by giving access to users and allowing them to provide feedback. More often, this type of testing is known as beta testing. The developer performs this to view and understand the user's point of view.

What are the advantages of functional testing?

The advantages of functional testing services are mentioned below:
• Helps in getting rid of errors in software.
• Ensures that users are satisfied.
• It ensures the proper functioning of all the components of a software or application.
• It ensures security and safety against cyber attacks.

What are the disadvantages of functional testing?

The disadvantages of functional testing services are as follows:
• Functional testing can miss out on evaluating thoroughly critical and logical errors in the system.
• It may involve some degree of repetitiveness when multiple test cases are designed to cover similar functionality or processes.
• Also, this testing mainly relies on clear and well-defined user requirements. Yet, user requirements are not always readily available or may lack clarity.

Thus, functional testing guarantees a strong foundation of a top-grade software product that adheres to requirements.

What is non functional testing?

Unlike functional testing in software testing, non functional system testing includes parameters such as performance and other non functional characteristics. Also, non functional system testing includes various aspects such as performance testing, usability testing, security testing, and compatibility testing. Simply, it can be said that non functional testing gives in-depth knowledge about the application behavior.

Key types of non functional system testing include:

• Load Testing: Load testing is about testing the software’s capacity to handle fluctuating loads. Simply, Loading capacity means more and more people can work on the system simultaneously.
• Performance Testing: It checks how well the software performs under various workloads and usage conditions.
• Usability Testing: It is all about testing the software’s user-friendliness and overall user experience.
• Security Testing: It is used to detect the security flaws of the software application. It is basically done to get an idea of weaknesses in a system that may lead to software being more prone to cyber-attacks.
• Compliance Testing: Each developer has to maintain a set of rules and regulations while developing software or application. So, this test mainly checks for how accurately the software aligns with the compliance guidelines.

What are the advantages of non functional testing?

The advantages of non functional testing are as follows:
• It improves the performance of the application or software.
• Takes much less time compared to other testing.
• Provides a higher level of security which helps to safeguard the software from cyber attacks.
• Non functional testing also addresses compliance requirements, ensuring that the software adheres to industry standards.

What are the disadvantages of non functional testing?

The disadvantages of non functional testing are as follows:
• Non functional testing is a bit heavy on dependencies required as it requires specific tools, environments, and expertise. This, in turn, leads to an increase in resources like time, manpower, and budget.
• This testing can require additional time compared to functional testing.
• Whenever software gets a new update, developers have to perform this test each time.

Non functional testing guarantees that the software not only operates correctly but also delivers an enjoyable user experience, regardless of the difficulties it might face throughout. Therefore, we can say that non functional testing comes under black-box testing as it does not focus on internal code structure. Rather, it focuses on the system's outer nature or behavior.

How do functional and non functional testing differ?

This is a major concern for new developers. Most of the newcomers in this field often confuse themselves between functional and non functional testing. Differences are as follows:

1. Functional testing mainly focuses on software functionality, operations, and actions. At the same time, non functional testing focuses on the software's capability to take loads and perform optimization.
2. Functional testing verifies the operations based on business requirements. In contrast, non functional testing checks the application's behavior.
3. Functional testing notes the requirements of users, whereas non functional testing notes user expectations.
4. Developers require a checklist process and documentation needed. In the case of non functional testing, developers need to test it on various scenarios.
5. The compiler compiles the code after the functional test. It's vice versa in the case of non functional testing.
6. Functional testing can be performed manually, whereas developers perform non functional testing using automated tools.
7. Developers start with functional testing at first to ensure a proper design outline and move on to non functional testing after tuning the performance parameter.

Go through the functional and non functional testing example below to have a broader idea:

Suppose you are creating a website for a company. Of course, the website or webpage will have multiple components to help users. Now, whenever any user opens the website, the first thing displayed to the user is the login page. The login page has various components, such as username and password options. To place and format the login page properly, developers use functional testing. On the other hand, non functional testing ensures that the login page loads within minimum time following the time complexity parameter.


So, while testing softwares, it is essential to understand that there is no single solution. In this domain of software development, achieving success depends on how well both functional and non functional testing is used. So, a developer is able to create top-grade applications when he knows how to combine both functional and non functional testing. Proper use of both satisfies user needs and paves the way to becoming the best software.



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