There is an eclipse plugin that can do this (and more) for you : moreunit  ; but it can do a lot of other interesting things like automatically move the test class when you move a class :

suppose that I've got a class named MyClass in src/main/java/com/gisgraphy/package and the test class MyClassTest in gisgraphy/src/test/java/com/gisgraphy/package and i move MyClass to src/main/java/com/gisgraphy/other/package with the Eclipse refactor tool, the test class MyClassTest will be automatically moved to src/test/java/com/gisgraphy/other/package. when you'll read the documentation, i'm pretty sure you'll install and use it !

Enjoy :)