host: Change tests to serve test realm fetches in-page - #5717
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…rker Host tests serve http://test-realm/* URLs through a service worker that relays them to the in-browser mock realm. The worker only intercepts once it controls the page and its per-module activation has been acked, so a fetch issued before that window closes escapes to the real network and fails — test-realm is not a real host. When the fetch is fire-and-forget (a card component loading a realm's _types summary as it renders), the rejection surfaces as a QUnit global error and fails the whole shard rather than a single test. The test fetch wrapper now answers requests whose URL falls under a registered test realm via realm.maybeHandle. The registry is populated at realm construction, before any component can render, so this path has no startup window. A request the realm declines still falls through to the network, and non-fetch resources (images, workers) continue to rely on the service worker. Module-loading latency normally hides the race: base card modules are fetched and transpiled before their components can render, which takes long enough that the worker is ready. Anything that shortens that path re-exposes it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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August 7, 2026 22:59
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As the host test suite gets faster, there’s a race condition that has been increasing instability: the
test-realmservice worker can only intercept requests once it’s been set up and activated, soFailed to fetchhappens with theRETRY_PATTERNuntil it comes up. In #5653, where I experimented with bundling@cardstack/baseinstead of as a realm, theFailed to fetchwent from ≈400/run to ≈2500/run.This serves test realm directly instead of through a service worker. The tests that work with
img,audio,videoetc do exercise the service worker so this test-only override doesn’t mean the worker has no test coverage.