London |ITP-Jan-2026| Ping Wang|spint 3 | 2-practice-tdd

[pathywang]

• I have titled my PR with Region | Cohort | FirstName LastName | Sprint | Assignment Title
• My changes meet the requirements of the task
• I have tested my changes
• My changes follow the style guide

Changelist

I did code then use node to check then use npm test to check test file function

[github-actions]

Your PR's title isn't in the expected format.

Please check the expected title format, and update yours to match.

Reason: Sprint part (spint 3) doesn't match expected format (example: 'Sprint 2', without quotes)

If this PR is not coursework, please add the NotCoursework label (and message on Slack in #cyf-curriculum or it will probably not be noticed).

If this PR needs reviewed, please add the 'Needs Review' label to this PR after you have resolved the issues listed above.