fix(test): resolve a timing issue in fake_peer_set setup

[arya2]

Motivation

To fix a mempool test that's failing occasionally.

Closes #5384

Solution

• Wait for AdvertiseBlock earlier (i.e. before potentially adding transactions to the mempool)

Related cleanups:

• Replace unreachable!(..) with assert!(added_transactions.is_empty(), ..) in the Nil case where the response is being unwrapped with a match statement
• Update unreachable and assert messages to say MempoolTransactionIds requests should respond Ok(Vec<UnminedTxId> | Nil)

Review

This is low priority.

Reviewer Checklist

• Will the PR name make sense to users?
  • Does it need extra CHANGELOG info? (new features, breaking changes, large changes)
• Are the PR labels correct?
• Does the code do what the ticket and PR says?
• How do you know it works? Does it have tests?

[teor2345]

@arya2 this seems to close ticket #5384, so I added it to the PR description.

Also, I think this CI failure might be a high priority, we've got multiple reports.

[teor2345]

Let's give it a shot!

[teor2345]

This fix does not work on macOS:

timeout while waiting for a request
in zebra_test::mock_service::MockService<zebra_network::protocol::internal::request::Request, zebra_network::protocol::internal::response::Response, zebra_test::mock_service::PanicAssertion, alloc::boxed::Box<dyn std::error::Error+core::marker::Send+core::marker::Sync>>

https://github.com/ZcashFoundation/zebra/actions/runs/3238058141/jobs/5305848404#step:14:10158

[teor2345]

We need a fix that works on macOS, or we need to turn off this test on macOS.

[arya2]

@teor2345 Thank you for updating the PR description.

We need a fix that works on macOS, or we need to turn off this test on macOS.

Not a MacOS-specific issue, it caused a timeout while waiting for a request for the AdvertiseBlock. I removed the wait for tip change and moved AdvertiseBlock above where the mempool storage is being accessed.

[codecov]

Codecov Report

Merging #5398 (a53eba8) into main (8e5425f) will decrease coverage by 0.05%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5398      +/-   ##
==========================================
- Coverage   79.10%   79.05%   -0.06%     
==========================================
  Files         308      308              
  Lines       39752    39752              
==========================================
- Hits        31447    31427      -20     
- Misses       8305     8325      +20     

[teor2345]

This seems to work now