Please read my comment on github about saving the localStorage reference and recovering this one.

You cannot add that to the suiteTeardown. IMHO you should run your algorithm programmatically in a asynchronous test

test('Ev.me migration successful >', function(done) {
  // Run migration....
  assert.isTrue(!localStorage['userHistory'] && !localStorage['localShortcuts'] && !localStorage['localShortcutsIcons']);
  done();
});