PR-21771 "Remove test helpers aliases in test.support" was just merged.  It needs an immediate followup to document the new locations of constants and functions.  The now dead entries in test.suppport doc must be moved into new support module docs, with whatever revisions. As of this moment, the module index has
test
  test.support
  test.support.script_helper
So temp_dir, for instance, is still documented as part of test.support, which it no longer is, instead of the undocumented test.support.os_helper, where it now exclusively resides.