Overview of Unit Testing

Get familiar with unit testing and its use cases for software applications.


There are several types of software application testing that are commonly used in the software development lifecycle to ensure the quality and reliability of software applications. Some of the most common types of software application testing are integration testing, system testing, performance testing, unit testing, etc. The different levels of testing are typically performed in a specific order, following a hierarchical approach. In this course, we’ll be solely focusing on unit testing.

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Testing hierarchy
Testing hierarchy

What is unit testing?

Unit testing is a critical software testing technique used to validate the behavior and functionality of individual units or components in a software application. Automated testing tools are used to ensure that the units are working as intended and meet the specified requirements. By conducting unit testing early in the development cycle, defects can be identified and addressed while they are still relatively inexpensive and easier to fix. This helps in reducing the risk of errors in the final software product and improving the overall user experience.

Unit testing also promotes better code design and modularity by encouraging developers to write modular and loosely coupled code that is easier to test and maintain. It can also improve code reuse and reduce the overall development time and costs by detecting issues early in the development cycle and reducing the need for manual testing and debugging.

Refactoring is the process of improving the design of code without changing its external behavior. Unit tests can help ensure that refactoring does not introduce defects into the application.

Unit tests serve as a form of documentation for the components of the application. They describe the expected behavior of each unit, which can be useful for developers who need to understand how the application works.


In summary, unit testing is an important software testing technique that helps ensure the quality and reliability of software applications. It can improve the development process by reducing the risk of errors, promoting better code design and modularity, and improving the overall efficiency and effectiveness of the software development process.