Unit Testing Vs. Functional Testing

Which Is Right For Your Needs: Unit Or Functional Testing?

June 11, 2020Posted By: Sailesh Bhambhani
Functional TestingSoftware TestingUnit Testing


Do you know that globally, there are over 7 billion smartphone users, and over 80% of businesses use at least one Software as a Service (SaaS) application in their operations? Not only that, nearly 90% of businesses use cloud services.

It indicates that almost every individual and business uses at least one software, be it for personal or professional usage. It has opened paths for software developers to craft value-creation systems according to the user’s requirements.

However, not all software is immensely popular and receives tremendous response from the audience. There are numerous reasons behind this, one of which is that the software is not being tested thoroughly.

Hence, this blog will provide valuable information to simplify your software testing process. We will simplify your selection process by shedding light on two crucial software testing types that have established prominent names – unit and functional testing.

Whether you are aiming for high quality, reliability, or any other aspect, this blog will answer most of your queries and ease your software development process. Let’s get started. It will equip you with essential information to make informed decisions to improve your software’s performance and user satisfaction.

Understanding Unit Testing

We will first start by understanding unit testing. We will explain its objectives, importance, and advantages. Then, we will do the same for functional testing. This will give you better clarity on key points in both software testing types, which will be helpful during the software testing stage.

Definition Of Unit Testing

Unit testing is the backbone of software quality assurance (QA), as it involves testing individual units or components of a software app. Wondering what a unit is? Well, it is the smallest testable part of any software system. It could be a function, class, or method. Moreover, unit testing aims to verify that each unit performs as intended in isolation from the rest of the software system.

Objectives Of Unit Testing

The primary objective of unit testing is to validate the functionality of particular coding sections of the software during the development phase. It helps identify and fix errors before they create any adverse effects. Most importantly, it ensures that each component works as independently as expected.

Importance Of Unit Testing

After reading its objectives, you will have a brief idea that it plays a pivotal role in software development. Unit testing promotes modular code design, improving both maintainability and accuracy.

Moreover, it allows for individual units of the software to be tested in isolation, ensuring every part functions perfectly on its own. It facilitates simplification of troubleshooting and debugging processes.

Furthermore, the significance of unit testing extends to lowering project costs. By detecting errors beforehand in the development process, fixing bugs at that stage is cost-effective rather than in later phases or post-release.

Also, unit testing serves as a form of documentation by giving clear guidelines on what the code is expected to do. It is highly beneficial for revisiting older codebase segments and even briefing new developers about the software.

Additionally, unit testing is crucial during updates and software scaling. It empowers developers to make changes, add new features, or remove existing ones with the assurance that it won’t affect the current functionalities. As a result, it maintains the integrity and performance of the software app as it evolves.

Advantages Of Unit Testing

There are numerous advantages of unit testing. However, we will walk you through salient ones.

  • Easier Code Maintenance: Unit tests make the codebase straightforward to maintain and comprehend, as each part is clearly defined and validated.
  • Reduced Debugging Time: Detecting bugs in the unit testing phase makes it easier to resolve them immediately so they don’t affect the software later.
  • Enhanced Code Quality: Regularly conducting unit testing ensures higher code quality and excellent functionality because it encourages developers to consider all edge cases.
  • Improved Efficiency: Lastly, unit testing enables developers to work faster and more efficiently as they receive prompt feedback on the coding, facilitating quick adjustments.

To summarize, unit testing helps maintain software apps by keeping them functioning and performing as intended.

Understanding Functional Testing

Now, we will move to functional testing and discuss its objectives, importance, and advantages. We will first start with a quick definition.

Definition Of Functional Testing

Functional testing is a black-box testing type that evaluates whether the software app complies with its defined specifications. It primarily focuses on testing the software application’s features and operational behavior to ensure they meet the documented requirements.

Objectives Of Functional Testing

The chief objective of functional testing is to test the software app from the end user’s perspective. It not only ensures that software performs as intended but also verifies whether the final product will match the user’s needs in real-world scenarios.

Importance Of Functional Testing

Functional testing is paramount in the software development cycle as it confirms the software app’s intuitiveness and user-friendliness. It ensures that the final product aligns with end users’ expectations and business objectives.

Moreover, functional testing is crucial as it validates the software’s usability and focuses on user interactions, data handling, and overall system operations. All these are key to user satisfaction and business success.

Furthermore, functional testing checks software app performance under various conditions, including load and stress tests. It helps to determine how software functions across different platforms and devices, ensuring compatibility and robustness.

Functional testing also validates the smooth integration of various system components. It is crucial for complex systems where flawless module interaction is a must.

Nonetheless, functional testing ensures that all units of the systems work cohesively by simulating real-world usage scenarios. It provides valuable insights for delivering a stable and dependable user experience. It is vital for the successful deployment and functioning of the software.

Advantages Of Functional Testing

Let us walk you through the fundamental advantages of functional testing before turning to its applications.

  • Comprehensive Coverage: It tests the software app comprehensively from start to finish, ensuring all user flows perform as intended.
  • Validates Business Logic: Functional testing confirms business logic and user requirements by ensuring the software behaves as expected under different scenarios.
  • Detects Interface Issues: It identifies problems in the user interface (UI) that aren’t detectable at the unit level.

The thorough approach of functional testing ensures your software meets all operational and user requirements and, most importantly, functions correctly.

Applications Of Unit & Functional Testing

Now, we will walk you through the applications of both testing types before jumping to the final verdict. Let us first start with unit testing uses.

Unit Testing Applications

  • Development Phase: It is highly beneficial during the initial software development stages, creating small, independent code blocks and integrating new features.
  • Pre-Release Checks: Before integrating various components, unit tests ensure that each component’s existing functionality remains unaffected by code changes and works as intended in isolation.

Functional Testing Applications

  • Before Software Release: Functional tests are essential for validating that the final product meets all functional requirements of end-users and the system and is ready for deployment.
  • During System Updates: It is helpful to update the software with new features or remove existing ones. It ensures that existing functionalities are intact by new integrations. It keeps developers worry-free so that any changes do not affect current coding.

To summarize, each testing type has its suitable applications. It is wiser to use the blend of both approaches to thoroughly evaluate your software app performance, functionality, and usability.

Verdict: Which One Is The Best?

In this section, we will answer the million-dollar question of this blog—which one should you choose between unit testing and functional testing?

  1. Firstly, we suggest not seeing both testing types as a proposition. Instead, focus on the strengths and appropriate context for each to determine the most effective one for your testing strategy.
  2. Secondly, we suggest using both testing types simultaneously to get a comprehensive overview of your software health. Unit testing will ensure individual components perform as expected, while functional testing confirms these components interact correctly within the entire software system.
  3. Lastly, combining both testing methodologies is ideal if utmost precision and robustness are paramount for your projects. For instance, in financial and healthcare software, both testing methodologies deliver the best quality assurance.
    However, if your project is smaller and less complex, you should prioritize functional testing to ensure your software meets end-user expectations.


After reading the blog, you will be equipped with firm clarity about unit and functional testing objectives, importance, advantages, and applications. You will have obtained additional information from the three points of verdict to determine the ideal one for your software development projects.

Also, aim to incorporate both testing types as they are critical to creating robust and high-quality software. Depending on your project’s complexity and requirements, integrate both testing methodologies for a comprehensive evaluation, ensuring your final product meets all technical functionalities and end-user expectations.

We suggest connecting with a software developer or software testing expert, as they will recommend the most suitable testing methods for your software app. However, if you have any questions or need more clarification, feel free to contact us.

If you ever wish to simplify the software testing process with the assistance of industry experts, ZealousWeb is just one contact away. Our software testing teams have delivered premier-quality final products to clients, ensuring the software meets end-user expectations and performs correctly under different load scenarios in real-world applications.

Enhance your users’ satisfaction and product reliability by taking the first step of an initial consultation with our professionals at hello@zealousweb.com. We are happy to help.


How Does Functional Testing Differ From Unit Testing?

What Is Unit Testing In Software Development?

When Should Unit Testing Be Performed During The Development Process?

Can Functional Testing Be Automated Like Unit Testing?

Which Testing Method Is More Important For Software Quality Assurance?

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