Unit testing is a fundamental practice in software development used to verify that individual units of code (e.g., functions or methods) work as expected. It involves testing small, isolated units of code in isolation from the rest of the application. The main goal is to ensure that each unit performs its intended functionality correctly.

Key Points about Unit Testing:

• Isolation: Each unit is tested in isolation, meaning that external dependencies are replaced with mock objects. This ensures that test results are not affected by the behavior of other components.

• Fast Execution: Unit tests are designed to be quick to execute, allowing developers to run them frequently during development.

• Automation: Unit tests are automated, which means they can be run automatically whenever there are code changes or as part of a continuous integration (CI) process.

• Code Coverage: The aim is to achieve high code coverage, meaning that as many lines of code as possible are tested to detect potential bugs.