Sam Pierson's Blog

When developing a new module using TDD, I like to first write a failing test, then write the code to make the test pass, then repeat ad-nauseum.  If you are using autospec/autotest – which I love in general – it has this annoying habit of running the entire suite of tests on any red to [...]

For completeness: to install ZenTest Autotest:

sudo gem install ZenTest

Autotest will display a red/green bar after running tests, if you add this line to ~/.autotest

require ‘autotest/redgreen’

More plugins are described here, but this appears to be the only one that works out of the box.