fix: deflake //rs/tests/ckbtc:ckbtc_minter_update_balance_head_nns

[basvandijk]

Root Cause

The assert_temporarily_unavailable function in rs/tests/ckbtc/src/utils.rs called .expect() on the agent's update_balance result, which panics on transport errors. The test failed with a TCP-level timeout (hyper::Error(Io, Kind(TimedOut))) when making an HTTP request to the replica node. This is a transient infrastructure/networking issue, but the function did not handle it, causing the test to fail instead of retrying.

Fix

This PR was created following the steps in .claude/skills/fix-flaky-tests/SKILL.md.

[Copilot]

Pull request overview

Deflakes the ckbtc_minter_update_balance_head_nns test by preventing transport-level timeouts from immediately failing the test when the ledger canister is intentionally stopped.

Changes:

• Updated assert_temporarily_unavailable to retry on ic_agent transport errors (e.g., HTTP timeouts) instead of panicking.
• Extended assert_temporarily_unavailable to accept a Logger and use retry_with_msg_async! for structured retries.
• Updated the ckbtc_minter_update_balance test to pass the logger into assert_temporarily_unavailable.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
rs/tests/ckbtc/src/utils.rs	Adds retry logic for agent transport errors in assert_temporarily_unavailable and updates imports/signature accordingly.
rs/tests/ckbtc/ckbtc_minter_update_balance.rs	Updates the test call site to match the new helper signature (passes logger).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.