I noticed that TestSolrProperties and TestEmbeddedSolrServer were really similar. They both worked on the test-files folder, but the last one cleaned everything at the end, while the second one not.
I created a base class to avoid copy pasting the same code, then I changed both to work on a temp directory, without modifying anything on the test-files folder.
Regarding the other elevate-data-distrib.xml problem mentioned in the
SOLR-3268, I had a look at it. It seems to copy the core/src/test-files/solr/conf/elevate.xml to same path but different filename (elevate-data-distrib.xml) right before testing. Then the test uses the new file and doesn't clean it at the end. Well, I wonder why the test makes that copy. Maybe I didn't get something, but rather than cleaning at the end, my patch removes that copy and the test seems to work anyway. Let me know if there's a better fix for this!