fix(FN-3460): fix numerical rounding errors during report upload

sw-mattw commented 1 month ago

Introduction :pencil2:

During bank report upload to portal, we occasionally observe floating-point rounding errors for numerical cells. These are presented as validation errors (see screenshot below), meaning the report cannot be submitted.

Facility utilisation values of 3938753.80 and 761579.37 are two examples of this.

A spreadsheet with this issue has been attached to the ticket itself.

This affects production.

Validation errors for the above figures: Note that the value displayed in Excel (3938753.80) does not match the value in the entry column of the first row (due to this rounding issue).

369045787-3683f4e4-c47e-4884-a6e4-0b8918516b42

Resolution :heavy_check_mark:

Added a handler function to handle any floating-point rounding errors and correct these
- Checks if the rounded 2 decimal place value is within 1e-6 of the original figure. If it is, we take the rounded value, otherwise we use the original figure. This approach means we can still handle genuine errors such as 12.345 (which isn't 2 DP, but is not a floating-point rouding error either).
Updated valid report spreadsheets in the e2e tests to include the two rows with the above problematic facility utilisation values.

Miscellaneous :heavy_plus_sign:

N/A

codecov-commenter commented 1 month ago

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 33.17%. Comparing base (1f4b137) to head (8922903).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## release-2.0.1 #3546 +/- ## ============================================== Coverage 33.16% 33.17% ============================================== Files 1397 1398 +1 Lines 31254 31256 +2 Branches 5002 5002 ============================================== + Hits 10366 10368 +2 Misses 18266 18266 Partials 2622 2622 ``` | [Flag](https://app.codecov.io/gh/UK-Export-Finance/dtfs2/pull/3546/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=UK-Export-Finance) | Coverage Δ | | |---|---|---| | [api-test](https://app.codecov.io/gh/UK-Export-Finance/dtfs2/pull/3546/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=UK-Export-Finance) | `0.39% <ø> (ø)` | | | [unit-test](https://app.codecov.io/gh/UK-Export-Finance/dtfs2/pull/3546/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=UK-Export-Finance) | `33.43% <100.00%> (+<0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=UK-Export-Finance#carryforward-flags-in-the-pull-request-comment) to find out more.

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