I posted recently about the new remote mode feature of the Selenium RC plugin. One thing I forgot to mention is that this feature can also be used to run your Selenium tests interactively against a running app instance. You can start your app as normal using
grails run-app then either open a second terminal or background the process (Ctrl-Z in a bash shell) then use
grails -Dselenium.remote=true test-app other:selenium _<test name>_ to run individual tests without stopping or re-starting the app. With the app running development mode you can effectively test-drive using Selenium tests and Grails' artefact reloading capabilities.
One thing I should clarify is that direct domain class access will not work in remote mode. I’m thinking about ways to add fixtures support to the Selenium RC plugin so there’s a good alternative approach that will work in remote mode.