Alexandra says, "don't say i haven't told you." atticus makes the humorous reply that he'd "never say that," alluding to the fact that alexandra comments on everything. this is an example of

I believe the answer is: Irony

In literature, Irony refers to the use of humorist effect while the situation may actually signifies the opposite.
This type of language is most commonly used when there is something going on to the character's mind while the character is conversing with others

It is state and federali really hope this