So you have all your tests in selenium 1.x code and you want to run the tests in Firefox 4. Thanks to Selenium 2.0 (which supports FF4 and IE9), this can be achieved easily. Here is what you have to do
1. Download Selenium 2.0 standalone server from here
2. Copy this jar file to /seleniumgridfolder/vendor
3. Delete the existing jar file which starts with selenium-server*.jar
4. Open the grid_configuration.yaml file under the seleniumgrid installation folder
5. Add a new browser under environments as given below
– name: “*firefox4”
browser: “*firefox C:\Program Files\Mozilla Firefox 4.0 Beta 11\firefox.exe (Or whatever is the path to Firefox.exe”
6. Launch your Hub.
7. Launch RC with environment as *firefox4
That’s it! Your tests will now run in Firefox 4.