tests(store-sync): fix flaky reconciliation test on macOS by anchoring timestamps to a fixed baseTime and aligning sync window via offset

[NagyZoltanPeter]

Summary

Fix a flaky reconciliation test in tests/waku_store_sync/test_protocol.nim that intermittently failed on macOS due to timestamp drift between message creation and the reconciliation sync window.

Root cause

• The test created message timestamps using getNowInNanosecondTime() while the reconciliation time window was computed separately via calculateTimeRange().
• On macOS, slower scheduling meant those separate "now" calls diverged enough to misalign the intended sync window and the generated message timestamps.
• Result: messages expected to be “in-window” were sometimes treated as “out-window,” causing assertions like:
  • remoteNeeds.len == 0 while diffInWin == 18

Solution

• Anchor all test time calculations to a single fixed baseTime captured once at the start of the test.
• Define the intended sync window as [baseTime - 1s, baseTime].
• Align the reconciliation’s effective “now” with baseTime by passing an explicit offset:
  • offset = actualNow - baseTime
  • Because calculateTimeRange(now, jitter) uses now = getNow() - jitter, setting jitter = actualNow - baseTime yields now_effective = baseTime.
• Generate messages deterministically:
  • 18 in-window messages strictly inside the window with 50 ms margins from both ends.
  • 20 out-window messages placed well before the sync window to avoid overlap.
• Use consistent signed int64 arithmetic for timestamp math.

Implementation details

• File changed: tests/waku_store_sync/test_protocol.nim
  • Capture baseTime once and compute syncWindowStart/End from it.
  • Create in-window and out-window message timestamps relative to baseTime with clear buffers.
  • Compute timeOffset = actualNow - baseTime and pass it to storeSynchronization(offset = timeOffset) so the window is [baseTime - 1s, baseTime].
  • Ensure all timestamp operations use int64 to avoid signed/unsigned pitfalls.

Verification

• macOS: make test tests/waku_store_sync/test_protocol.nim passes locally.
  • Reconciliation correctly detects 18 in-window messages and ignores the 20 out-window messages.
• Recommendation: run CI matrix (macOS + Ubuntu) to validate cross-platform stability.

Scope / Risk

• Test-only change; no production reconciliation logic altered.
• Eliminates timing race by ensuring a deterministic relationship between message timestamps and the sync window.

Notes

• Consider extracting test time helpers for future tests that depend on stable time ranges.

[Copilot]

Pull Request Overview

Fix a flaky reconciliation test on macOS by implementing deterministic timestamp handling to eliminate timing race conditions between message creation and sync window computation.

• Anchors all time calculations to a single fixed baseTime to prevent timestamp drift
• Aligns the reconciliation sync window with message timestamps using a calculated offset
• Replaces relative timestamp calculations with absolute positioning based on the fixed base time

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[Copilot]

The magic number 50_000_000'i64 (50ms) is repeated. Consider extracting it as a named constant like BUFFER_MARGIN_NS to improve maintainability and make the buffer size configurable.

[github-actions]

You can find the image built from this PR at

quay.io/wakuorg/nwaku-pr:3619

Built from 4f435a4

[SionoiS]

Ah clever! It use the offset as a way to fix the time window.

[Ivansete-status]

LGTM! Thanks for it! 💯

[NagyZoltanPeter]

Seems still not ok. Now ci/test-ubuntu-22.04 failed with this exact test case (While macos ci succeeded):

2025-10-08T16:33:09.8707124Z ===============================================================
2025-10-08T16:33:09.8714059Z   /home/runner/work/nwaku/nwaku/build/all_tests_waku 'Waku Sync: reconciliation::sync 2 nodes, 40 msgs: 18 in-window diff, 20 out-window ignored'
2025-10-08T16:33:09.8714677Z ---------------------------------------------------------------
2025-10-08T16:33:09.8715235Z     /home/runner/work/nwaku/nwaku/tests/waku_store_sync/test_protocol.nim(605, 26): Check failed: remoteNeeds.len == diffInWin
2025-10-08T16:33:09.8715888Z     remoteNeeds.len was 12
2025-10-08T16:33:09.8716090Z     diffInWin was 18
2025-10-08T16:33:09.8716551Z     /home/runner/work/nwaku/nwaku/tests/waku_store_sync/test_protocol.nim(609, 28): Check failed: deliveredHashes in inWinHashes
2025-10-08T16:33:09.8717055Z     deliveredHashes was 0x5862...86a6