My team and I are hosting our project's repository on Google Code. We would like to have a Continuous Integration setup so that when modifications are made, it tries to build the project and run the tests to make sure that everything's okay. From what I hear, a solution to this is to have an external machine listen to the repository for changes, then grab the updated files and try to build it, etc.
My question is how to set up this scenario with a Google Code repository.