The AppRenderer "live theme flip" test had its inner `waitFor` raised twice
(bare assertion -> 1000ms -> 5000ms) and failed a third time at 5032ms under
`local:gate` load. The budget was never the problem.
Root cause: happy-dom 20.11.1's `MutationObserverListener` stores its dispatch
callback as `new WeakRef((record) => this.report(record))` — an arrow function
nothing else holds strongly. A GC between `observe()` and the mutation collects
it, `callback.deref()` returns undefined in `Node[reportMutation]`, and the
mutation is dropped silently and permanently. That is why the failure tracks
machine load rather than any wall-clock value, and why no raise ever fixed it.
Reproduced directly against 20.11.1: an observer on `documentElement`, three
forced `global.gc()` passes, then `setAttribute` — callback count 0. Without
the forced GC, 1. Upstream holds the arrow strongly in a private field from
20.11.2 onward; the same probe against the bumped copy reports 1.
So:
- bump `happy-dom`'s floor to `^20.11.2` (lockfile resolves 20.14.5), which is
the actual fix;
- replace the 5000ms `waitFor` with `flipThemeAttributeAndAwaitObservers`, an
awaited condition per AGENTS.md: a probe MutationObserver registered after
the component's is notified after it, so resolving on the probe's callback
proves the component's already ran. No polling, no timeout, nothing
load-sensitive.
- use the same helper in the two negative theme tests, which is what makes
their "not called" a real gate rather than a vacuous pass on a flip that was
never delivered.
The file's 52 tests now run in ~120ms.
Closes#2384
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Signed-off-by: cliffhall <cliff@futurescale.com>
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