Mocking is the act of replacing a function with a fake copy and optionally, configuring it to return some predefined data. The primary use case for mocking is unit testing. Mocking frameworks allow you to replace a specific call to a class or method with a behavior you define. Thanks to this ability, you can easily test units of code in isolation without messing up their dependencies
These are the 11 best C# Mock libraries in 2022, NSubstitute - A friendly substitute for .NET mocking libraries; FakeItEasy - The easy mocking library for .NET; WireMock.Net - flexible library; pact-net - .NET version of Pact; moq.spikes - The most popular and friendly mocking framework for .NET.