This is to add the eclipse launchers from HADOOP-5911 to the 0.20 security branch.
Eclipse has a notion of "run configuration", which encapsulates what's needed to run or debug an application. I use this quite a bit to start various Hadoop daemons in debug mode, with breakpoints set, to inspect state and what not.
This is simply configuration, so no tests are provided. After running "ant eclipse" and refreshing your project, you should see entries in the Run Configurations and Debug Configurations for launching the various hadoop daemons from within eclipse. There's a template for testing a specific test, and also templates to run all the tests, the job tracker, and a task tracker. It's likely that some parameters need to be further tweaked to have the same behavior as "ant test", but for most tests, this works.
This also requires a small change to build.xml for the eclipse classpath.