WS-NA: Temporal Migration (PR 1: Freeze current behavior with characterization tests)

[Isabella-Mitchell]

Resolves JIRA: WS-NA - 10% time. See plan

Summary

Increases test coverage in preparation for moment -> JS migration work

Code changes

What I added

Deterministic relative-time and DST edge coverage in index.test.js

• Made the existing “9 hours ago” utility test deterministic by mocking Date.now.
• Added DST start boundary assertions for Europe/London:
  -- 28 March 2021, 00:30 GMT
  -- 28 March 2021, 02:30 BST
• Added DST end boundary assertions for Europe/London:
  -- 31 October 2021, 01:30 BST
  -- 31 October 2021, 01:30 GMT
• Added threshold-boundary characterization assertions for current Moment config:
  -- 59m59s -> 59 minutes ago
  -- 60m -> an hour ago
  -- 23h59m59s -> 23 hours ago
  -- 24h -> a day ago
  -- 29d23h59m59s -> 29 days ago
  -- 30d -> a month ago
  -- 11 months -> 11 months ago
  -- 12 months -> a year ago
• Added cleanup so moment.now is reset after tests.

Test-only helper for deterministic timestamp formatting in testUtils.js

• Added export formatTimestamp for direct timestamp-based characterization checks without touching fixture snapshots.

DST characterization cases in timeFormat.test.js

• Added explicit DST start/end formatting checks via the new test helper.
• Kept existing expectedFormats matrix untouched.

Testing

1. Unit tests pass

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