Between the forms of testing mentioned above is testing GeoServer by hand, issuing a number of requests to ensure that nothing major was broken. To do this we highly recommend using the 'demo' section of the web administration tool. This allows you to easily issue 'post' requests, by just filling them into the form. And you can also put pre-configured requests that you use a lot in the 'demo' folder. See the section on the CITE folder for more information about flexible build configurations (also see 4 GeoServer Data Directory. We recommend making use of these for joint debugging, so that developers are assured of having exactly the same set up.

The best way to get acquainted with how to write tests is to look at the current tests, and model your tests after those. We also recommend trying Test Driven Development, that is, if you are going to write a new interface or method then you write the test first, and then the code to solve the exact problem. For more information on test driven development go here.