Understanding unit testing

In C#, unit tests are automated tests written to verify the behavior of a small, isolated piece of code known as a unit. The goal of unit testing is to ensure that the unit behaves as expected and meets the requirements and specifications defined for it.

A unit test should test the functionality of the unit in isolation, without relying on any external dependencies, such as a database or web service. The isolation of the unit test ensures that any failures are caused by issues within the unit being tested, rather than external factors. This means that unit tests are fast, efficient, and provide rapid feedback to the developer.

Unit tests should cover all relevant scenarios and edge cases for the unit being tested, including both valid and invalid input values. This helps to ensure that the unit behaves correctly in all possible situations. Unit tests should also be maintainable, meaning that they can be easily updated as changes are made to the code...