Glasgow | 26-ITP-May | Niangh Ciang | Sprint 3 | Implement and rewrite tests

[Niangh-Ciang]

Self checklist

• 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

Implemented all three functions and rewrote their test suites using Jest.
Covered all required cases including valid, boundary, and invalid inputs.

[github-actions]

The changed files in this PR don't match what is expected for this task.

Please check that you committed the right files for the task, and that there are no accidentally committed files from other sprints.

Please review the changed files tab at the top of the page, we are only expecting changes in this directory: ^Sprint-3/1-implement-and-rewrite-tests/

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.

[github-actions]

The changed files in this PR don't match what is expected for this task.

Please check that you committed the right files for the task, and that there are no accidentally committed files from other sprints.

Please review the changed files tab at the top of the page, we are only expecting changes in this directory: ^Sprint-3/1-implement-and-rewrite-tests/

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.

[github-actions]

The changed files in this PR don't match what is expected for this task.

Please check that you committed the right files for the task, and that there are no accidentally committed files from other sprints.

Please review the changed files tab at the top of the page, we are only expecting changes in this directory: ^Sprint-3/1-implement-and-rewrite-tests/

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.

[github-actions]

The changed files in this PR don't match what is expected for this task.

Please check that you committed the right files for the task, and that there are no accidentally committed files from other sprints.

Please review the changed files tab at the top of the page, we are only expecting changes in this directory: ^Sprint-3/1-implement-and-rewrite-tests/

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.