ZIP-200: Test that mempool storage is cleared when a network upgrade activates

[teor2345]

Motivation

When a network upgrade activates, the mempool needs to redo validation with the new consensus rules.

Specifications

While the current chain tip height is below ACTIVATION_HEIGHT, nodes SHOULD NOT accept transactions that will only be valid on the post-upgrade consensus branch.

When the current chain tip height reaches ACTIVATION_HEIGHT, the node's local transaction memory pool SHOULD be cleared of transactions that will never be valid on the post-upgrade consensus branch.

https://zips.z.cash/zip-0200#memory-pool

It is possible for a reorganization to occur that rolls back from after the activation height, to before that height. This can handled in the same way as any regular chain orphaning or reorganization, as long as the new chain is valid.

https://zips.z.cash/zip-0200#chain-reorganization

Designs

Tasks can await network upgrade activation using ChainTipChange::tip_change and TipAction::Reset:

zebra/zebra-state/src/service/chain_tip.rs

Line 313 in 44ac067

pub async fn tip_change(&mut self) -> Result<TipAction, watch::error::RecvError> {

Solution

Make sure the implementation satisfies the consensus rules:

• Reject transactions that are invalid for the current network upgrade #2806
• Clear mempool each time the network upgrade changes #2761
• Test rollback and multiple activations of the same network upgrade

[teor2345]

* Test rollback and multiple activations of the same network upgrade

@upbqdn we're running the same reset code for network upgrade activation and rollbacks.
Do our existing tests cover multiple resets?

If we don't need any extra tests, we can just close this ticket.

[teor2345]

I renamed this ticket to match the remaining work.