Add comprehensive tests for currencyToAmount in util.ts

[coderabbitai]

Background

The currencyToAmount function in packages/loot-core/src/shared/util.ts has been the source of several bugs recently:

• PR Fix currencyToAmount incorrectly converting input #4383 fixed an issue where the function expected a string in the current number format
• PR fix negative amount parsing #4489 fixed a regression related to parsing negative amounts

Currently, there are tests for looselyParseAmount and number formatting functions in util.test.ts, but none specifically for currencyToAmount. This is a critical utility function that handles currency string parsing throughout the application.

Objective

Add comprehensive unit tests for the currencyToAmount function covering:

• Handling of different number formats (comma-dot, dot-comma, space-comma, apostrophe-dot, comma-dot-in)
• Proper parsing of negative amounts (both with minus sign and parentheses)
• Edge cases like leading zeros, only decimal part, etc.
• Handling of invalid inputs

Related PRs and Issues

• Fix currencyToAmount incorrectly converting input #4383 - Original fix for currency conversion
• fix negative amount parsing #4489 - Fix for negative amount parsing
• [Bug]: Reconciling Loan Account Taking Negative Balance as Positive #4487 - Issue that revealed the negative amount parsing bug

Suggested Test Cases

Test cases should include but not be limited to:

• Basic positive amounts with various formats
• Negative amounts (both with minus sign and parentheses)
• Amount strings with no decimal part
• Amount strings with only decimal part (e.g., .45)
• Strings with incorrect format (e.g., using dot in dot-comma format)
• Invalid inputs (non-numeric strings)

This will help prevent regressions and ensure consistent behavior across the application.