The issue is obsolete with respect to the minimal test implied by the opening message.  At least two tests (added since this was written) read the .def files.

Some of the proposed tests are, now at least, redundant  For boolean tests like
    self.assertIn(get('editor-on-startup', 'bool'), (True, False))
a non-boolean value results in a Warning (treated like error), the assert, and remaining tests are skipped, and IDLD hangs.  Stripping strings should not be needed.

Some of the tests should be part of a startup check of default *and* user options.  Values should also be checked when changed (they mostly are).

Since new options have been added, some tests are missing.

I would like to have a 3-layer option map that can be used for both runtime change and the test suite.