Visual Studio has a unit test engine, where you can write you unit tests (TDD, Unit Testing, …).
If you need a short (but full!) tutorial to start writing your own unit tests, read A Unit Testing Walkthrough with Visual Studio Team Test by Mark Michaelis.
It also will cover refactoring and code coverage items. 
With the latest release of Visual Studio Test System (VSTS) comes a full suite of functionality for Visual Studio Team Test (TT). Team Test is a Visual Studio integrated unit-testing framework that enables:
-Code generation of test method stubs.
-Running tests within the IDE.
-Incorporation of test data loaded from a database.
-Code coverage analysis once the tests have run.
In addition, Team Test includes a suite of testing capabilities not only for the developer, but the test engineer as well.[...]
more info about Visual Studio Products, here Updated: Visual Studio 2008 Product Comparison Guide by Rob Caron
Technorati tags: Visual Studio, Agile, Unit Testing, Refactoring, Code Coverage
