GitHub repository: kmusick/fluentassertions
Primary language: C#
Description: A very extensive set of extension methods that allow you to more naturally specify the expected outcome of a TDD or BDD-style unit tests. Targets .NET Framework 4.7, .NET Core 2.1 and 3.0, as well as .NET Standard 2.0 and 2.1. Supports the unit test frameworks MSTest2, NUnit3, XUnit2, MSpec, and NSpec3.