Fix Windows-incompatible Jest tests by robhogan · Pull Request #1937 · react/metro

robhogan · 2026-09-17T11:16:33Z

scripts/jestFilter.js skipped 25 test suites on Windows. Most of them failed because of posix assumptions in the tests rather than in Metro, so this fixes the tests and removes them from the skip list to run in Windows CI.

The tests still assert the same things, but filesystem paths are written as posix and passed through the existing p() helpers (posixToSystemPath, createPathNormalizer), so on Windows they're realistic C:\... paths. Client-facing values - URLs, httpServerLocation, sourceURLs, specifiers, package.json keys - are still asserted with forward slashes on every platform.

Suites parameterised over posix and win32 now mock node:path with path.posix for the posix half, rather than the host's path (which is path.win32 on Windows). metro-resolver's getPackageForModule test helper also looped forever on Windows and hung three suites, because path.win32.parse('/root').root is / but dirname returns \.

Still skipped on Windows:

api-snapshots-sync-test.js - flow-api-translator emits os.EOL line endings in generated comments, and API snapshots are only meaningfully generated on posix.
js-test.js and symbolicate-test.js, which expose real Windows bugs. Fix backslashes in async bundle paths on Windows #1938 and Fix symbolication of stack traces with Windows absolute paths #1939 fix and unskip them.

Changelog: Internal

Test plan:
Windows CI on this PR - every suite passes except the three still skipped, whose Windows failures are exactly the bugs above.

meta-codesync · 2026-09-17T14:56:01Z

@vzaidman has imported this pull request. If you are a Meta employee, you can view this in D120534260.

Copilot

Copilot review overview

🟢 Approval recommended

No unresolved blocking issues are identified.

Review effort: Lite
Findings: None

What changed in this PR

Updates Metro’s Jest tests for Windows compatibility by removing POSIX-only assumptions and obsolete Windows skips.

Changes:

Normalizes filesystem paths across affected test suites.
Corrects platform-specific mocks and resolver traversal.
Retains only documented Windows skips.

File	Description
`scripts/jestFilter.js`	Updates the Windows skip list.
`packages/metro/src/Server/__tests__/Server-test.js`	Normalizes filesystem paths.
`packages/metro/src/node-haste/lib/__tests__/AssetPaths-test.js`	Uses native path inputs.
`packages/metro/src/DeltaBundler/Serializers/helpers/__tests__/js-test.js`	Makes module paths portable.
`packages/metro/src/DeltaBundler/__tests__/resolver-test.js`	Uses POSIX path mocks.
`packages/metro/src/DeltaBundler/__tests__/Graph-test.js`	Normalizes graph paths.
`packages/metro/src/DeltaBundler/__tests__/DeltaCalculator-test.js`	Corrects POSIX mock behavior.
`packages/metro/src/DeltaBundler/__tests__/buildSubgraph-test.js`	Normalizes subgraph paths.
`packages/metro/src/__tests__/HmrServer-test.js`	Normalizes module paths.
`packages/metro/src/__tests__/Assets-test.js`	Uses platform-aware filesystem paths.
`packages/metro-transform-worker/src/__tests__/index-test.js`	Removes incompatible transformer filesystem setup.
`packages/metro-symbolicate/src/__tests__/symbolicate-test.js`	Normalizes absolute-path snapshots.
`packages/metro-resolver/src/__tests__/utils.js`	Fixes Windows package traversal.
`packages/metro-resolver/src/__tests__/symlinks-test.js`	Normalizes symlink paths.
`packages/metro-resolver/src/__tests__/platform-extensions-test.js`	Normalizes resolver paths.
`packages/metro-resolver/src/__tests__/package-exports-test.js`	Makes export tests portable.
`packages/metro-resolver/src/__tests__/index-test.js`	Makes resolver expectations portable.
`packages/metro-resolver/src/__tests__/browser-spec-test.js`	Normalizes browser resolution paths.
`packages/metro-resolver/src/__tests__/assets-test.js`	Normalizes asset paths.
`packages/metro-resolver/src/__tests__/__snapshots__/index-test.js.snap`	Removes the replaced path-dependent snapshot.
`packages/metro-file-map/src/crawlers/__tests__/node-test.js`	Tests both path platforms.
`packages/metro-file-map/src/__tests__/index-test.js`	Normalizes file-map paths and messages.
`packages/buck-worker-tool/src/__tests__/worker-test.js`	Uses POSIX paths for the mocked filesystem.

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robhogan · 2026-09-28T12:21:40Z

@vzaidman - thanks for the stamp but since it's been imported I can't merge it from here - D120534260 needs to land.

vzaidman · 2026-09-28T13:03:56Z

I'll land it

vzaidman · 2026-09-29T15:04:26Z

@robhogan please rebase and land it. I unlinked it from the imported PR.

Summary: `scripts/jestFilter.js` skipped 30 test suites on Windows. Most were failing because of posix assumptions in the tests themselves, not Metro. This fixes those tests and removes them from the skip list, so they run in Windows CI. The fixes remove posix assumptions without weakening what's asserted: - Filesystem paths in inputs and expectations are written as posix and made portable with the existing `p()` helpers (`posixToSystemPath`, `createPathNormalizer`), so tests use realistic `C:\...` paths on Windows. - Client-facing values - URLs, `httpServerLocation`, `sourceURL`s, specifiers, package.json keys - stay asserted with forward slashes on every platform. - Suites parameterised over `posix`/`win32` now mock `node:path` with `path.posix` for the posix half, rather than the host's `path`, which on Windows is `path.win32`. - `metro-resolver`'s `getPackageForModule` test helper looped forever on Windows (`path.win32.parse('/root').root` is `/` but `dirname` returns `\`), hanging three suites. - Some inline and file snapshots embedding absolute paths are replaced by exact assertions built with `p()`. Still skipped on Windows: - `api-snapshots-sync-test.js` - `flow-api-translator` emits `os.EOL` line endings in generated comments. API snapshots are only meaningfully generated on posix. - `js-test.js` and `symbolicate-test.js` - these expose real Windows bugs, fixed and unskipped in the next commits in this stack. Changelog: [Internal] Test Plan: Windows CI on this PR: all suites pass except the three still skipped, whose failures on Windows are exactly the product bugs described above. ``` yarn jest Test Suites: 148 passed, 148 total yarn flow check yarn lint ```

#1937 runs Server-test and the metro-transform-worker tests on Windows against a platform-aware `metro-memory-fs`, so the asset URL tests added here, written against POSIX paths, failed there after merging main. They now build their paths with `posixToSystemPath`, as the rest of those files do, and the metro-transform-worker test gets the same platform-aware in-memory filesystem as `Assets-test`. `metro-resolver` becomes a devDependency of `metro-transform-worker` for the helper.

meta-cla Bot added the CLA Signed This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed. label Sep 17, 2026

robhogan force-pushed the pr1937 branch 2 times, most recently from a566848 to 7138ab8 Compare September 17, 2026 11:47

robhogan changed the title ~~Run all Jest tests on Windows~~ Fix Windows-incompatible Jest tests Sep 17, 2026

robhogan added this pull request to stack #1940 September 17, 2026 11:47

robhogan marked this pull request as ready for review September 17, 2026 11:49

facebook-github-tools Bot added the Shared with Meta Applied via automation to indicate that an Issue or Pull Request has been shared with the team. label Sep 17, 2026

robhogan force-pushed the pr1937 branch from 7138ab8 to fa3821e Compare September 23, 2026 14:08

robhogan requested review from vzaidman and a lite review from Copilot September 23, 2026 14:09

Copilot started reviewing on behalf of robhogan September 23, 2026 14:09 View session

Copilot AI reviewed Sep 23, 2026

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robhogan mentioned this pull request Sep 26, 2026

Fix backslashes in async bundle paths on Windows #1938

Merged

kwy404 mentioned this pull request Sep 26, 2026

Fix exact "exports" and "imports" keys with no target falling back to a pattern #1987

Merged

robhogan mentioned this pull request Sep 26, 2026

Fix symbolication of stack traces with Windows absolute paths #1939

Open

vzaidman approved these changes Sep 28, 2026

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robhogan force-pushed the pr1937 branch 2 times, most recently from 5c51121 to 2d1913b Compare September 29, 2026 16:04

robhogan force-pushed the pr1937 branch from 2d1913b to 1479fd5 Compare September 29, 2026 16:48

robhogan merged commit 13604e0 into main Sep 29, 2026
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Fix Windows-incompatible Jest tests - #1937

Fix Windows-incompatible Jest tests#1937
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robhogan commented Sep 17, 2026 •

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