def METHOD_NAME(self):
    ic = IdentityCompare()
    ic.on_trait_change(self.bar_changed, "bar")
    self.reset_change_tracker()
    default_value = ic.bar
    ic.bar = self.a
    self.check_tracker(ic, "bar", default_value, self.a, 1)
    ic.bar = self.different_from_a
    self.check_tracker(ic, "bar", self.a, self.different_from_a, 2)