I have partial memory recollection of product for .NET and Visual Studio that runs impacted unit tests right after you change one line or something like that. It has some smart code impact detection and test scheduler. Does anyone know anything about such product? I've forgotten even how to google for it.
Seems that Google keywords for finding the product I was looking for.net were
parallel test runner
which, with my .NET affiliation that Google knows about, led me to article on Smart Continuous Test-Runner For .NET – For Free. NCrunch was the one I was looking for, but found out about AutoTest.NET and Mighty Moose which are nice alternatives.
Hard part is to figure out which tests to run for change of certain source file.
Nose-knows builds this relationships from coverage analysis: Announcement - for Python.
It is on my list to try in my copious free time.