The Visual Studio Unit Testing Framework describes Microsoft's suite of unit testing tools as integrated into some[1] versions of Visual Studio 2005 and later.
Unit tests created with the unit testing framework can be executed in Visual Studio or, using MSTest.exe, from a command line.
The attribute is used to identify classes that contain test methods.
The attribute is used to identify methods that contain unit test code.
An assertion is a piece of code that is run to test a condition or behavior against an expected result.