Would do that or would have done it?

Is there a situation in which following sentence is correct?

"You could have mentioned you would do that"

If so, then in which context is it right? I mean, if the sentence is started by "could have" then the next part should contain "have" after "would" in this case? Is this a rule or does it all depend on the situation in which you're using it? And if so, please present me the right context.

Yes, it's allowed. We're looking back, to look forwards again.

Consider a situation where one housemate leaves some drugs lying around. The second housemate finds them and flushes them down the toilet.

Housemate A: Err did you see that little bag I left by the phone?

B: What, the drugs? Yes, I flushed them down the loo.

A: WHAT??! Why?

B: I don't want any drugs in my house. My sister's kids come round here all the time. So, if I see any drugs I will just flush them.
A: You could have mentioned you would do that.

B: The subject never came up before.

The tenses already match in my opinion.
One of the meanings for 'would' is:

used as the past form of will when reporting what somebody has said or thought He said he would be here at eight o'clock (= His words were: ‘I will be there at eight o'clock.’).
She asked if I would help. They told me that they probably wouldn't come. Oxford Advanced Learner's Dictionary 9th edition © Oxford University Press, 2015