A while ago at PDC, a couple of my colleagues presented CHESS but unfortunately weren’t ready to release it. Well, you don’t have to wait anymore: CHESS is now available for download at DevLabs for Visual Studio 2008 Team Dev or Team Test. CHESS comes under the same pre-release license as Pex or under an academic license.

CHESS = Unit Testing of Concurrent Programs

CHESS is a tool that finds and reproduces “Heisenbugs” in concurrent programs (both Win32 and .NET)… You know those kind of bugs that do not reproduce under the debugger or only in production environment, the kind of bugs where you scratch your head for days in front of a process dump before giving up.

I also recently recorded a great ‘getting started’ CHESS tutorial for CHESS in Visual Studio Unit Test: you can take a unit test*** and turn it into a CHESS test by adding the [HostType(“Chess”)] attribute!

*** That unit test should involve threads, otherwise CHESS will have not effect.

CHESS and Pex

In order to control the scheduling of .NET programs, CHESS instruments the threading APIs using ExtendedReflection, the code instrumentation framework that was built for Pex. In the future, we would also like to combine both approach to explore data inputs and thread schedules together.

Well enough said… go and try it out!