Improve mathUtils.test.js - Better Coverage & Maintainability

[SophiaLi20]

Hey ,
I’d like to propose some improvements to mathUtils.test.js to enhance its test coverage, maintainability, and robustness. Before opening a PR, I’d love to get your thoughts on these changes.

Proposed Changes:
Refactor toDirection tests using test.each - This makes test cases cleaner and reduces redundancy.
Add edge case tests for invalid inputs -Ensure toDirection properly handles non-numeric values (null, undefined, NaN, strings).

Enhance calculateMidpoint tests by:

• Handling large number of stops (performance testing).
• Ensuring identical points return the same location correctly.
• Standardize lon usage instead of mixing lng and lon for consistency.

Implementation Plan:

• Refactor toDirection tests using test.each to reduce duplication.
• Add edge case handling for invalid inputs (null, undefined, NaN).
• Expand calculateMidpoint tests:
  Test with large datasets (1000+ stops).
  Verify identical stops return the same result.
• Ensure consistent variable naming (lon instead of lng).

Relevant File:
mathUtils.test.js