[LOW] [Splits] [$500] Individual split amount is inconsistent for manual and scan split bill

[lanitochka17]

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Version Number: 1.4.35-0 Reproducible in staging?: Y Reproducible in production?: Y If this was caught during regression testing, add the test name, ID and link from TestRail: https://expensify.testrail.io/index.php?/tests/view/4254803 Email or phone of affected tester (no customers): Logs: https://stackoverflow.com/c/expensify/questions/4856 Expensify/Expensify Issue URL: Issue reported by: Applause - Internal Team Slack conversation:

Action Performed:

1. Create a group with another two users
2. Create a scan split with a $6.50 receipt
3. Create a manual $6.50 split
4. After scan split is complete, navigate to 1:1 DM with one of the split members

Expected Result:

Since the split amount for both manual and split scan requests is the same, which is $6.50, the individual split amount should be the same for both types of request

Actual Result:

The individual split amount for Scan split request is $2.16, while it is $2.17 for Manual split request

Workaround:

Unknown

Platforms:

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

• [x] Android: Native
• [x] Android: mWeb Chrome
• [x] iOS: Native
• [x] iOS: mWeb Safari
• [x] MacOS: Chrome / Safari
• [x] MacOS: Desktop

Screenshots/Videos

Add any screenshot/video evidence

https://github.com/Expensify/App/assets/78819774/8e5bd4a0-1107-48da-841b-c00faf025aa3

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[melvin-bot[bot]]

Job added to Upwork: https://www.upwork.com/jobs/~01680f4e130a8667a2

[melvin-bot[bot]]

Triggered auto assignment to Contributor-plus team member for initial proposal review - @alitoshmatov (External)

[melvin-bot[bot]]

Triggered auto assignment to @CortneyOfstad (Bug), see https://stackoverflow.com/c/expensify/questions/14418 for more details.

[lanitochka17]

We think that this bug might be related to #vip-split-p2p-chat-groups

[allgandalf]

Proposal

Please re-state the problem that we are trying to solve in this issue.

Individual split amount is inconsistent for manual and scan split bill

Inconsistency in duplicate distance error in distance creation and edit flow

What is the root cause of that problem?

In MoneyRequestPreview, we wrap the total amount in a convertToDisplayString

https://github.com/Expensify/App/blob/b6363778127003ce5ecb7375c30bb5d05d77b7d9/src/components/ReportActionItem/MoneyRequestPreview.js#L342-L343

And hence as you can see in the video attached, there we see both the manual as well as scan split amount same, but in individual page view, we don't do so with scanned split bill

What changes do you think we should make in order to solve the problem?

Wrap the individual split bill amount in convertToDisplayString as well

What alternative solutions did you explore? (Optional)

N/A

[alitoshmatov]

@GandalfGwaihir I don't think that is related

[alitoshmatov]

When opening a 1:1 DM and money request there, backend is sending two different values for scan and manual:

@CortneyOfstad Can we get an internal engineer to take a look at this

[CortneyOfstad]

Sounds good!

[melvin-bot[bot]]

Auto-assigning issues to engineers is no longer supported. If you think this issue should receive engineering attention, please raise it in #whatsnext.

[melvin-bot[bot]]

Current assignee @alitoshmatov is eligible for the Internal assigner, not assigning anyone new.

[CortneyOfstad]

Not overdue — waiting on an engineer to take a look

[alitoshmatov]

Looks like no engineer assigned to this issue

[CortneyOfstad]

@alitoshmatov No worries, that is what the hot pick tag is for. It allows engineers to know that this one is available if they have any free time to snag it 👍

[CortneyOfstad]

Still waiting on an engineering 👍

[melvin-bot[bot]]

@CortneyOfstad @alitoshmatov this issue was created 2 weeks ago. Are we close to a solution? Let's make sure we're treating this as a top priority. Don't hesitate to create a thread in #expensify-open-source to align faster in real time. Thanks!

[melvin-bot[bot]]

Current assignee @alitoshmatov is eligible for the External assigner, not assigning anyone new.

[CortneyOfstad]

Alright, checked with the team and this can be external, so going to correct the labels. Hopefully we'll get someone to bite, but if not, I'll reach out to CallStack if their team is interested 👍

[brandonhenry]

Proposal

Please re-state the problem that we are trying to solve in this issue.

The individual split amount is inconsistent between manual and scan split bills, resulting in a discrepancy of $0.01 in the split amount for a $6.50 bill.

What is the root cause of that problem?

We need to review the code responsible for calculating the individual split amounts in both manual and scan split scenarios. The issue likely lies in the rounding logic or the way the total amount is divided among participants when communicating between the frontend and backend.

1. Rounding Logic in iouUtils's calculateAmount:

• The rounding method in calculateAmount must be consistent for both scan and manual splits.
• The current rounding method needs a review to ensure it handles edge cases where the split amount does not divide evenly.

https://github.com/Expensify/App/blob/c8826dddb35a401faf35598a9ebc77c760c55335/src/libs/IOUUtils.ts#L33

2. Currency Conversion Logic in CurrencyUtils:

• The functions convertToBackendAmount and convertToFrontendAmount could be introducing rounding errors.
• The discrepancy might occur during the conversion of float to integer or vice versa, especially for currencies with more than two decimal places (which it does seem there is a comment indicating we don't support - are we still receiving that somehow?).

https://github.com/Expensify/App/blob/c8826dddb35a401faf35598a9ebc77c760c55335/src/libs/CurrencyUtils.ts#L81 https://github.com/Expensify/App/blob/c8826dddb35a401faf35598a9ebc77c760c55335/src/libs/CurrencyUtils.ts#L90

What changes do you think we should make in order to solve the problem?

1. Review and Update calculateAmount Function:

• Confirm the rounding method matches the desired business logic.
• Ensure that the currency's minor unit (e.g., cents) is correctly factored into the calculations.

2. Ensure Consistent Conversion Logic:

• Verify that the conversion logic in CurrencyUtils aligns with how the backend expects to receive and send out currency values.
• Adjust any conversion functions to handle currencies with more than two decimal places correctly.

[CortneyOfstad]

@alitoshmatov thoughts on the proposal above? I have a suspicion that the rounding logic is also affecting this, especially when off by a single cent.

[mvtglobally]

Issue not reproducible during KI retests. (First week)

[alitoshmatov]

@brandonhenry Thank you for your proposal but you are not suggesting any meaningful solution.

[alitoshmatov]

As of my finding this is definitely related to backend and cannot be handled by external engineers.

cc: @CortneyOfstad

[melvin-bot[bot]]

@CortneyOfstad @alitoshmatov this issue is now 3 weeks old. There is one more week left before this issue breaks WAQ and will need to go internal. What needs to happen to get a PR in review this week? Please create a thread in #expensify-open-source to discuss. Thanks!

[CortneyOfstad]

Thanks @alitoshmatov! Going to adjust this to internal 👍

[melvin-bot[bot]]

Current assignee @alitoshmatov is eligible for the Internal assigner, not assigning anyone new.

[CortneyOfstad]

Adjusted to show a "unassigned" — hopefully that will get eyes on this 👍

[CortneyOfstad]

This is considered "Low" Priority, so going to adjust this to Weekly 👍

[melvin-bot[bot]]

@CortneyOfstad @alitoshmatov this issue is now 4 weeks old and preventing us from maintaining WAQ. This should now be your highest priority. Please post below what your plan is to get a PR in review ASAP. Thanks!

[melvin-bot[bot]]

Triggered auto assignment to @miljakljajic (Bug), see https://stackoverflow.com/c/expensify/questions/14418 for more details.

[CortneyOfstad]

Hi @miljakljajic! I am heading OoO and will be back March 11th, so reassigned to have someone keep this moving until I am back. At this stage, we're waiting for internal engineers to snag this. Is pretty low priority but wanted to have someone watching just in case. Thanks!

[CortneyOfstad]

Back from OoO — thanks for holding down the fort @miljakljajic!

[mvtglobally]

Issue not reproducible during KI retests. (First week)

[CortneyOfstad]

I am also having trouble recreating this in testing. @alitoshmatov @lanitochka17 is anyone else able to recreate this consistently?

[CortneyOfstad]

@alitoshmatov @lanitochka17 bump on the comment above ^^^

[CortneyOfstad]

@alitoshmatov @lanitochka17 bump again — please provide update by EOD today, thank you!

[alitoshmatov]

Sorry @CortneyOfstad, I was having hard time scanning receipt other days.

I tried now and yes the issue is not reproducible

[CortneyOfstad]

No worries @alitoshmatov! Going to close as this is not reproducible 👍