-f/--fromfile <filename>
option.  This runs all and only the tests named in the file, in the
order given (although -x may weed that list, and -r may shuffle it).
Lines starting with '#' are ignored.

This goes a long way toward helping to automate the binary-search-like
procedure I keep reinventing by hand when a test fails due to interaction
among tests (no failure in isolation, and some unknown number of
predecessor tests need to run first -- now you can stick all the test
names in a file, and comment/uncomment blocks of lines until finding a
minimal set of predecessors).