I revised the patch a bit to fit better in the general scheme of things, see below.
Does this still do what you intended? I haven't run all tests yet, just this one....
1> puts the test case in the "usual" place so it's run with the rest of the unit tests.
2> creates a temporary directory with the relevant files in it for a multicore setup
3> adds a solr-multi.xml file to the test files so we have one available.
This now runs either in an IDE or as a stand-alone test.