If you have never visited Pex for fun before, we suggest you follow the tutorial.
Is it just for fun? The full version of Pex integrates into Visual Studio, and can be launched from the command line as well. (Download, Documentation) Pex can explore an entire project at once and can automatically generate a comprehensive test suite of traditional unit tests.
What is a puzzle? Each puzzle is either a small program with a statement that is tricky to reach, or it is a Coding Duel, which is an interactive programming challenge. You can use Code Contracts and even write Parameterized Unit Tests.
How does Pex work? Pex finds interesting input values by analyzing the behavior of the code, combining dynamic and static analysis, and using a constraint solver.
Can I use Pex for fun for teaching? Yes! Please follow our teaching tutorial.
I want to provide feedback. If you have found a bug, you can send a bug report directly to the Pex developers at firstname.lastname@example.org. You can also get in touch with the Pex developers for any other reason at email@example.com.