Early identification of bugs saves time and effort. Modern functional testing techniques transformed software development and empowered developers to create intelligent and creative solutions. Unit testing – one of the most popular types of software testing – assures that only the best product is released and reaches the end user.

What is Unit Testing?

Unit testing is a technique used to validate that “units” of the software (the smallest, repeatable and testable parts of an application) operate as intended. It breaks down the functionality of the system into more manageable pieces so that software developers can detect bugs and prevent the transition of these bugs to the following stages such as system, integration or even beta testing.

This powerful approach doesn’t ensure that there will be no bugs after the application deployment. Nevertheless, by analysing the smallest units of code earlier on and before integrating the application, developers can be confident that there are no bugs in the blocks developed.

How does unit testing work?

There are several kinds of software testing, each with a focus on testing for certain defects. The most broadly used approaches are white-box testing and black-box testing. This distinction describes the knowledge needed by the software tester. But let’s look at these differences:

• Black-box testing: This involves testing the overall functionality of a software module without prior knowledge of its internal structures. Therefore, the tester assesses user experience and verifies how the software is supposed to work for end-users. But not how it achieves that. As a result, he/she is not required to have a background in programming.

• White-box testing: This allows testers to examine the actual implementation of a software module and validate the internal architecture of a software system – its code, design, infrastructure, and integrations.

For unit testing, white-box testing is usually the most suitable option, particularly when the modules are smaller. As we shared, unit testing involves isolating code modules and assessing their performance. Considering that only when all the pieces are functioning will the system as a whole be able to operate, unit testing becomes important for software development.

The developer responsible for writing the piece of code should have the greatest insight into its work. Therefore, it is normally up to him/her to test the unit. Nevertheless, it can also be carried out by a QA tester.

Why is unit testing important?

Certain developers underestimate how valuable it is to write unit tests. But they sure recognise the many advantages of unit testing once they get used to performing this kind of method.

Develops an agile development process: Unit testing helps to minimise complexity and improve a product’s quality. Using proper unit tests can save time as well as resources and speed up the whole process.

Simplifies debugging: By testing small units, you can detect bugs at a very early stage and before they impact more parts of the integrated application. By running tests that cover specific pieces of code, developers can quickly identify when anything goes wrong and trace the source of the error.

Improves quality and performance: Unit testing is a valuable tool for improving the quality and performance of your codebase, making it less error-prone. Indeed, it holds a great impact on the quality of code when it is an integral part of the software development workflow. Regularly conducting unit tests allows developers to detect issues early on and address them before they grow into more serious ones. This leads to increased efficiency, reduced downtime, and reduced costs while ensuring high-quality software.

Provides effective documentation: One of the most important benefits of unit testing is the development of a useful living document of the product. Documentation details the expected behaviour of each piece of code, thus helping developers have a quick and comprehensive vision and understand the structure and features of the application.

Reduces development costs: When bugs are identified and corrected in the early stages through unit testing, the time and cost are reduced. Compared to an early fix, it will cost significantly more to fix these bugs if they are found at the later stages of development.

Enhances code coverage: Code coverage is a metric that helps you understand how much of your source is tested. For this, we use tools. By breaking an application down into the smallest testable components, unit testing helps increase your code coverage.