Please excuse me if it happens that I just can't search, but it seems that neither How to dev nor the Developer Guide explains how to test changes you made. Let's say I know the patch to apply, or changes to apply to an ebuild in order to fix FL-XXXX. How can I emulate the standard merging process to make sure once my fix will hit the tree, it will actually work? I don't think I am supposed to move my changes to /usr/portage/ :P. So I wonder what is the common way to do this.
Thanks in advance.