Unit testing is the practise of testing individual pieces of source code to see if they operate properly. Unit testing is a method of ensuring that an application's features are operating properly. When a change in one unit conflicts with the functioning of another, unit tests alert the developer. Modern unit testing frameworks are usually built using the same code as the system being tested. This allows a developer creating application code in C# to also create unit tests in the same language.

What do we understand by the Unit Testing Framework?

Unit testing frameworks are designed to make the unit-testing process as simple as possible. Those frameworks allow you to create Test Fixtures, which are.NET classes with particular properties that allow a Test Runner to recognise them.

Although unit testing may be done without such a framework, it is a complex, time-consuming, and laborious procedure.

There are several unit testing frameworks to choose from. Each framework has its own set of advantages, and which one is best depends on the features required and the development team's degree of experience. The following are some examples of unit testing frameworks:

• MSTest

• xUnit

• NUnit

What is Mocking?

When the unit being tested has external dependencies, mocking is utilised in unit testing. Mocking is used to isolate and focus attention on the code under test rather than the behaviour or state of external dependencies. Mocking replaces dependencies with carefully managed substitute objects that mimic the actual ones' behaviour. Fakes, stubs, and mocks are the three basic forms of replacement objects.

Mocking Frameworks — Mockito and EasyMock

When writing unit tests, it is often required to mock or stub dependencies.

Mocking is preferred to stubbing. There are a couple of great options for mocking in the Java world — Mockito and EasyMock.