## Summary
- Fixes the `setTimeout.clock` property not being properly deleted after
`jest.useRealTimers()` is called
- Previously, the property was set to `false` instead of deleted,
causing `hasOwnProperty` checks to return `true`
- This broke React Testing Library and other libraries that check for
fake timers using `Object.prototype.hasOwnProperty.call(setTimeout,
'clock')`
## Changes
- Added `JSValue.deleteProperty()` binding in Zig to call JSC's
`deleteProperty()` method
- Updated `setFakeTimerMarker()` in `FakeTimers.zig` to delete the
`clock` property when disabling fake timers
- Updated existing test in `test/regression/issue/25869.test.ts` to
verify correct behavior
- Added new regression test in `test/regression/issue/26284.test.ts`
## Test plan
- [x] Verified new test fails with system bun (before fix)
- [x] Verified new test passes with debug build (after fix)
- [x] Verified existing fake timer tests still pass
- [x] Verified test for issue #25869 passes with fix
Fixes#26284🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
## Summary
Fixes#25869
Two fixes to enable `jest.useFakeTimers()` to work with
`@testing-library/react` and `@testing-library/user-event`:
- Set `setTimeout.clock = true` when fake timers are enabled.
testing-library/react's `jestFakeTimersAreEnabled()` checks for this
property to determine if `jest.advanceTimersByTime()` should be called
when draining the microtask queue. Without this, testing-library never
advances timers.
- Make `advanceTimersByTime(0)` fire `setTimeout(fn, 0)` timers.
`setTimeout(fn, 0)` is internally scheduled with a 1ms delay per HTML
spec. Jest/testing-library expect `advanceTimersByTime(0)` to fire such
"immediate" timers, but we were advancing by 0ms so they never fired.
## Test plan
- [x] All 30 existing fake timer tests pass
- [x] New regression test validates both fixes
- [x] Original user-event reproduction now works (test completes instead
of hanging)
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>
