[HOLD for payment 2023-09-04] Greenline line doesn't appear after the mark of a message as unread (iOS)

[lanitochka17]

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Action Performed:

1. Navigate to a thread conversation with several messages
2. Mark a message as unread

Expected Result:

Green line "new" should be appeared. Verify the unread marked is displayed in the conversation history

Actual Result:

Greenline line doesn't appear after the mark of a message as unread

Workaround:

Unknown

Platforms:

Which of our officially supported platforms is this issue occurring on?

• Android / native
• Android / Chrome
• iOS / native
• iOS / Safari
• MacOS / Chrome / Safari
• MacOS / Desktop

Version Number: 1.3.56-14

Reproducible in staging?: Yes

Reproducible in production?: No

If this was caught during regression testing, add the test name, ID and link from TestRail:

Email or phone of affected tester (no customers):

Logs: https://stackoverflow.com/c/expensify/questions/4856

Notes/Photos/Videos: Any additional supporting documentation

Bug6173971_RPReplay_Final1692745969.mp4

Expensify/Expensify Issue URL:

Issue reported by: Applause - Internal Team

Slack conversation:

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[OSBotify]

👋 Friendly reminder that deploy blockers are time-sensitive ⏱ issues! Check out the open StagingDeployCash deploy checklist to see the list of PRs included in this release, then work quickly to do one of the following:

1. Identify the pull request that introduced this issue and revert it.
2. Find someone who can quickly fix the issue.
3. Fix the issue yourself.

[melvin-bot]

Triggered auto assignment to @marcaaron (Engineering), see https://stackoverflow.com/c/expensify/questions/4319 for more details.

[marcaaron]

Could this be related? @MonilBhavsar @gedu #18637

[marcaaron]

Gonna check to see if relate.

[marcaaron]

Hmm ... reverted that PR locally and it's still broken

[marcaaron]

Hmm this is not related to messages being threaded. It seems like the unread won't work with any message. Doesn't matter if it is a thread.

[marcaaron]

Ok so after a somewhat lengthy investigation... I have discovered that when we mark a report as "unread" it sets the lastReadTime to be later than than the last visible created. But only on iOS.

Basically, this logic is not working correctly:

App/src/libs/DateUtils.js

Lines 270 to 279 in 79ea923

	/**
	* @param {String} dateTime
	* @param {Number} milliseconds
	* @returns {String}
	*/
	function subtractMillisecondsFromDateTime(dateTime, milliseconds) {
	const date = zonedTimeToUtc(dateTime, 'Etc/UTC');
	const newTimestamp = subMilliseconds(date, milliseconds).valueOf();
	return getDBTime(newTimestamp);
	}

This is the offending PR -> #24446

I am guessing that date fns works differently in react-native or something, but not sure how.

Confirmed by rolling back main to right before it was merged.