[PM 30576]Make Invoice Response currency culture invariant

[cyprain-okeke]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-30576

📔 Objective

The FormatForProvider method in InvoiceExtensions was using culture-aware decimal formatting ({pricePerItem:F2} and {taxAmount:F2}), which caused test failures on machines with non-US locales. On systems with comma decimal separators (e.g., European locales), the formatting would produce "$8,00" instead of the expected "$8.00", causing the FormatForProvider_ComplexScenario_HandlesAllLineTypes test to fail.

Example failure:

Expected: "1 × Tax (at $8.00 / month)"
Actual:   "1 × Tax (at $8,00 / month)"

Solution

Updated the currency formatting to use CultureInfo.InvariantCulture when formatting decimal values, ensuring consistent output regardless of system locale:

1. Line 55: Changed tax line item price formatting from $"(at ${pricePerItem:F2} / month)" to string.Format(CultureInfo.InvariantCulture, "(at ${0:F2} / month)", pricePerItem)

2. Line 74: Changed invoice-level tax formatting from $"1 × Tax (at ${taxAmount:F2} / month)" to string.Format(CultureInfo.InvariantCulture, "1 × Tax (at ${0:F2} / month)", taxAmount)

3. Added import: Added using System.Globalization; to support CultureInfo.InvariantCulture

Impact

• ✅ Fixes test failures: Tests now pass consistently on all machines regardless of system locale
• ✅ Consistent formatting: Invoice currency values always use period (.) as decimal separator, which is correct for USD formatting
• ✅ No breaking changes: On en-US systems, output remains identical ("$8.00")
• ✅ Fixes locale-dependent bug: Systems with comma decimal separators now produce correct output

Testing

• All existing tests pass, including FormatForProvider_ComplexScenario_HandlesAllLineTypes
• Verified formatting is consistent across different system locales
• No changes to test expectations needed (tests already expected period format)

Related

This addresses the issue where PR #6622 attempted to fix the test by setting thread culture, but the root cause was in the implementation using culture-aware formatting. This fix addresses the root cause in the implementation itself.

📸 Screenshots

⏰ Reminders before review

• Contributor guidelines followed
• All formatters and local linters executed and passed
• Written new unit and / or integration tests where applicable
• Protected functional changes with optionality (feature flags)
• Used internationalization (i18n) for all UI strings
• CI builds passed
• Communicated to DevOps any deployment requirements
• Updated any necessary documentation (Confluence, contributing docs) or informed the documentation team

🦮 Reviewer guidelines

• 👍 (:+1:) or similar for great changes
• 📝 (:memo:) or ℹ️ (:information_source:) for notes or general info
• ❓ (:question:) for questions
• 🤔 (:thinking:) or 💭 (:thought_balloon:) for more open inquiry that's not quite a confirmed issue and could potentially benefit from discussion
• 🎨 (:art:) for suggestions / improvements
• ❌ (:x:) or ⚠️ (:warning:) for more significant problems or concerns needing attention
• 🌱 (:seedling:) or ♻️ (:recycle:) for future improvements or indications of technical debt
• ⛏ (:pick:) for minor or nitpick changes

[github-actions]

Checkmarx One – Scan Summary & Details – 4e343ff5-5868-4f65-829d-b6798a7b6675

Great job! No new security vulnerabilities introduced in this pull request

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 55.07%. Comparing base (6d69c9b) to head (501b929).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6812   +/-   ##
=======================================
  Coverage   55.07%   55.07%           
=======================================
  Files        1934     1934           
  Lines       85777    85777           
  Branches     7675     7675           
=======================================
+ Hits        47238    47245    +7     
+ Misses      36749    36741    -8     
- Partials     1790     1791    +1     

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