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Update vitest to 5 #2151
Description
vitest and @vitest/coverage-v8 stayed on 4.1.11 in the latest dependency sweep. Both must move
together (5.0.0).
Blockers found
jest-dom matcher types no longer resolve — 172 error TS2339 across the test suite:
toBeInTheDocument, toBeDisabled, toBeChecked, toHaveAttribute, toHaveTextContent, and
toHaveValue all report "does not exist on type Assertion<void, HTMLElement>". vitest 5 changed the
Assertion type, so @testing-library/jest-dom's module augmentation no longer merges in. Needs the
setup file and/or tsconfig types wiring updated.
Order-dependent test failure surfaced — packages/graph-explorer-proxy-server/src/app.test.ts:311
intermittently expects status 400 and receives 200 during a full-suite run, while passing when the
file runs alone. vitest 5 reuses workers across files by default, so state that used to be isolated
per file now leaks. It reproduced once and passed on two subsequent full runs, so it's intermittent —
worth tracking down rather than waiting for it to bite CI.
Acceptance
pnpm checks and pnpm test pass with vitest and @vitest/coverage-v8 at 5.x, and the proxy server
app tests pass repeatably in a full-suite run.
Important
Internal only — this issue is maintained by the core team and is not accepting external contributions.
Activity
kmcginnes commentedon Sep 10, 2026
Related: #1853 is an open spike on an intermittent flake in the same
app.test.ts. Its shared-mock hypothesis bears directly on the worker-reuse theory described above — vitest 5 reusing workers across files would expose exactly that kind of cross-file state leak. Worth reading the two together.mjuarros commentedon Sep 18, 2026
Correction to the second blocker in the description, surfaced while reviewing #2166.
This isn't accurate. Isolation didn't change between the two versions — both default
isolate: true. Confirmed by unpacking each package and readingconfigDefaults:isolateclearMockstruefalsetruetrueNeither the migration guide nor the v5.0.0 release notes mention an isolation change. What v5 added is a reporter hint, printed only when
isolateisn't set explicitly, which is almost certainly the source of the confusion. It shows up on every run of this suite:The "reuses workers across files" phrasing there describes what
isolate: falsewould do, not what v5 now does. 220 workers for 220 files is per-file isolation working as before.The order-dependent
app.test.ts:311failure is real but pre-existing and unrelated to the upgrade — root-caused to an unawaitedpipelineinapp.tsand tracked in #2190.The actual v5 default flip in this table is
clearMocks, which #2166 pins for the proxy server package.