[MelvinBot]

Explanation of Change

tests/ui/EditMerchantRulePageGuardTest.tsx › "fetches the rules collection when it is reached without one loaded" fails intermittently on main with Number of calls: 0 for GetRules (for example, test / test (job 8)). The runs merged immediately before and after it pass.

Why it flakes:

• Only the tests that need a specific fetch state stubbed API.read. The other tests (which seed a rule) mount the editor, and useRulesPrefetch sends a real GetRules. The default Jest fetch mock answers it with jsonCode: 200, so its successData sets RAM_ONLY_HAS_RULES_DATA_BEEN_FETCHED: true.
• That request goes through waitForWrites and the network middleware chain, so its response can land after the next test has already cleared Onyx. When it lands during the fetch test, the hook sees the collection as already fetched and never sends GetRules.
• The assertion also ran after a single batched tick, but GetRules only goes out after the fetch flags load from Onyx and the effect runs.

The fix:

• Stub API.read in beforeEach (and restore it in afterEach) for every test in the file, so no real GetRules response can leak into a later test.
• Wrap the GetRules assertion in waitFor.

This is a test-only change. App code is unchanged.

Fixed Issues

$
PROPOSAL:

Tests

// TODO: The human co-author must fill out the tests you ran before marking this PR as "ready for review"
// Please describe what tests you performed that validates your changed worked.

• Verify that no errors appear in the JS console

Offline tests

QA Steps

// TODO: The human co-author must fill out the QA tests you ran before marking this PR as "ready for review".
// Please describe what QA needs to do to validate your changes and what areas do they need to test for regressions.

• Verify that no errors appear in the JS console

PR Author Checklist

• I linked the correct issue in the ### Fixed Issues section above
• I wrote clear testing steps that cover the changes made in this PR
  • I added steps for local testing in the Tests section
  • I added steps for the expected offline behavior in the Offline steps section
  • I added steps for Staging and/or Production testing in the QA steps section
  • I added steps to cover failure scenarios (i.e. verify an input displays the correct error message if the entered data is not correct)
  • I turned off my network connection and tested it while offline to ensure it matches the expected behavior (i.e. verify the default avatar icon is displayed if app is offline)
  • I tested this PR with a High Traffic account against the staging or production API to ensure there are no regressions (e.g. long loading states that impact usability).
• I included screenshots or videos for tests on all platforms
• I ran the tests on all platforms & verified they passed on:
  • Android: Native
  • Android: mWeb Chrome
  • iOS: Native
  • iOS: mWeb Safari
  • MacOS: Chrome / Safari
• I verified there are no console errors (if there's a console error not related to the PR, report it or open an issue for it to be fixed)
• I verified any copy / text that was added to the app is either coming verbatim from figma or has been approved by marketing (in order to get marketing approval, ask the Bug Zero team member to add the Waiting for copy label to the issue)
• If a new code pattern is added I verified it was agreed to be used by multiple Expensify engineers
• I tested other components that can be impacted by my changes (i.e. if the PR modifies a shared library or component like Avatar, I verified the components using Avatar are working as expected)
• If new assets were added or existing ones were modified, I verified that:
  • The assets are optimized and compressed (for SVG files, run npm run compress-svg)
  • The assets load correctly across all supported platforms.
• If the PR modifies code that runs when editing or sending messages, I tested and verified there is no unexpected behavior for all supported markdown - URLs, single line code, code blocks, quotes, headings, bold, strikethrough, and italic.
• If the PR modifies a generic component, I tested and verified that those changes do not break usages of that component in the rest of the App (i.e. if a shared library or component like Avatar is modified, I verified that Avatar is working as expected in all cases)
• If the PR modifies a component related to any of the existing Storybook stories, I tested and verified all stories for that component are still working as expected.
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  • I verified that all the inputs inside a form are aligned with each other.
  • I added Design label and/or tagged @Expensify/design so the design team can review the changes.
• If the PR adds or modifies the UI:
  • I asked an AI agent to review the changes for accessibility issues and addressed its findings.
  • I tested with a screen reader (VoiceOver on macOS) and verified all new/changed elements are reachable with a logical focus order.
  • I verified all new/changed elements have meaningful accessible names and roles.
  • I verified state changes are announced (e.g. checked/unchecked, expanded/collapsed, selected).
• I added unit tests for any new feature or bug fix in this PR to help automatically prevent regressions in this user flow.
• If the main branch was merged into this PR after a review, I tested again and verified the outcome was still expected according to the Test steps.

Screenshots/Videos

Android: Native

Android: mWeb Chrome

iOS: Native

iOS: mWeb Safari

MacOS: Chrome / Safari

[aimane-chnaif]

@MelvinBot which PR caused this?

[MelvinBot]

Add rules engine types and merchant rule AST helpers (Expensify/App#100389), merged 2026-10-01, introduced this flake.

That PR added both the flaky test and the hook that sends the leaking GetRules:

• a41f4923e9 added useRulesPrefetch.
• 08b1366f5d added the test "fetches the rules collection when it is reached without one loaded". Only that test and a few others stub API.read.

Neither the test file nor the hook has changed on main since then. The flake has been possible since that merge, and it fails only when a leaked response lands at the wrong moment.

Evidence

• git log origin/main -- tests/ui/EditMerchantRulePageGuardTest.tsx: every commit is from krishna2323, and the last one is b0e37ce425 (2026-10-01). All of them belong to that PR.
• git log -S useRulesPrefetch: the hook first appears in a41f4923e9, which is part of the same PR.
• In tests/ui/EditMerchantRulePageGuardTest.tsx:65, API.read is stubbed only through a helper that some tests call. The tests at lines 112-128 mount the editor without the stub. Their real GetRules response can then set RAM_ONLY_HAS_RULES_DATA_BEEN_FETCHED during the test at line 140.

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