Had issue today with autospec never stopping, and found this article, but I did have the autotest-rails gem installed.  Thanks to Mario Aquino’s article here, I learned that you can pass -v to autospec/autotest and it will print out what triggered it to run.  My culprit was rerun.txt, and then I found buried in the Cucumber documentation:

If you find that autotest runs your features continuously, your features may be changing a file which autotest is monitoring as they run. Use a setting like this to ignore such files. You’ll likely need to set autotest to ignore “rerun.txt” as well.

So, to your project’s .autotest or at ~/.autotest, add something like this:

Autotest.add_hook :initialize do |at|
%w{.svn .hg .git vendor rerun.txt}.each {|exception| at.add_exception(exception)}
end

At least, that’s what my ~/.autotest has, and after adding rerun.txt in there, everything is good.

Hopefully this will help someone else googling for the same thing I was with no luck.