def METHOD_NAME(self):
    nc = NoneCompare()
    nc.on_trait_change(self.bar_changed, "bar")
    self.reset_change_tracker()
    default_value = nc.bar
    nc.bar = self.a
    self.check_tracker(nc, "bar", default_value, self.a, 1)
    nc.bar = self.a
    self.check_tracker(nc, "bar", self.a, self.a, 2)