Test: Prototype shared Vite server for Node and jsdom projects

[ciampo]

What?

Follow up to #82687.

Prototype a nested Vitest project for the Node and jsdom suites so they inherit one configuration and share one Vite server. Browser Mode remains a separate project.

This also re-tests fsModuleCache; it is not enabled by this PR.

Why?

Node and jsdom currently build separate Vite module graphs. Vitest 5 can share a server between nested inline projects, but the first prototype rooted its referenced configuration under test/unit and discovered no integration tests.

How?

• Add a repository-root proxy for the referenced Node/jsdom project container. This preserves the existing repository-relative include paths.
• Move shared Vite and test options to the container, then keep the Node and jsdom projects inline so Vitest reuses one server.
• Normalize nested project labels in routing checks and validate cleanup defaults in both configuration files.
• Update the focused CI project selector. Browser Mode stays independent.

Benchmark notes

On the #82687 merge commit, five alternating runs used shard 1/8, four workers, seed 80855, and the same 134 files / 3,476 tests each time.

• Separate servers: 52.4s median, 55.3s mean.
• Shared server: 47.7s median, 59.2s mean.

The shared server improved the median by 9.0%, but two slow samples made the mean 7.0% worse. This remains a prototype rather than a stable performance claim.

A separate three-run warm-cache comparison improved both the median (42.6s vs 46.0s) and mean (43.9s vs 47.3s). However, priming took 97.0s, the single-shard cache occupied 84 MB across 5,959 files, and fsModuleCache does not support Browser Mode. It remains disabled.

Testing Instructions

1. Run npm run test:unit:routing. Confirm it validates 1,071 Vitest files, with every test assigned exactly once.
2. Run DEBUG=vitest:projects npm exec --no -- vitest list --config=test/unit/vitest.config.mjs --filesOnly. Confirm unit (jsdom) reuses the Vite server created for unit (node) and Browser Mode creates a separate server.
3. Run npm run test:unit:vitest -- --project='unit (node)' test/unit/scripts/test/discover-test-files.test.js test/unit/scripts/test/test-infrastructure-policy.test.js.
4. Run npm run test:unit:vitest -- --project='browser (chromium)'.
5. Run npm run build and npm run typecheck.

Testing Instructions for Keyboard

Not applicable. This PR does not change UI behavior.

Screenshots or screencast

Not applicable.

Use of AI Tools

Codex was used to prototype the configuration, add tests, run benchmarks, and draft this PR. The resulting diff and verification output were reviewed before publication.

[github-actions]

🤖 PR meta 🤖

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📦 Bundle size

Size Change: 0 B

Total Size: 8 MB

_{52a0d36 Run}

⚡ Performance

Show the results

Client side metrics exclude the server response time.

front-end-block-theme

Metric	7624e29	trunk	% Change
timeToFirstByte	48 ms +2.4% -2.08%	50.25 ms +5.67% -8.56%	-4.48%
largestContentfulPaint	84 ms +7.14% -4.76%	86 ms +9.3% -6.98%	-2.33%
lcpMinusTtfb	34.35 ms +23.29% -5.97%	34.5 ms +20.87% -9.13%	-0.43%
wpBeforeTemplate	22.68 ms +3.84% -1.37%	23.37 ms +15.15% -5.61%	-2.95%
wpTemplate	21.26 ms +3.06% -3.48%	21.49 ms +2.42% -4.93%	-1.07%
wpTotal	44.25 ms +3.05% -1.69%	46.77 ms +6.18% -8.85%	-5.39%
wpMemoryUsage	7.52 MB +0% -0%	7.48 MB +0% -0%	0.46%
wpDbQueries	17 +0% -0%	17 +0% -0%	0%

front-end-classic-theme

Metric	7624e29	trunk	% Change
timeToFirstByte	36.45 ms +2.61% -2.06%	36.3 ms +5.51% -1.79%	0.41%
largestContentfulPaint	88 ms +2.27% -0%	88 ms +4.55% -0%	0%
lcpMinusTtfb	52.05 ms +2.11% -1.92%	52.15 ms +0.77% -1.53%	-0.19%
wpBeforeTemplate	20.58 ms +2.48% -1.51%	20.55 ms +1.85% -1.61%	0.15%
wpTemplate	12.75 ms +2.82% -2.59%	12.98 ms +2.08% -3.31%	-1.77%
wpTotal	33.6 ms +2.44% -2.59%	33.38 ms +5.69% -1.38%	0.66%
wpMemoryUsage	5.51 MB +0% -0%	5.47 MB +0% -0%	0.64%
wpDbQueries	14 +0% -0%	14 +0% -0%	0%

media-processing

Metric	7624e29	trunk	% Change
mediaProcessingJpeg	413.49 ms +1.5% -2.21%	409.92 ms +0.89% -0.83%	0.87%
mediaProcessingAvif	6273.37 ms +0.17% -0.44%	6249.14 ms +0.14% -0.01%	0.39%
mediaProcessingJpegToAvif	4294.79 ms +0.19% -0.07%	4289.03 ms +0.17% -0.06%	0.13%

media-upload

Metric	7624e29	trunk	% Change
jpegUploadProcessing	1441.94 ms +36.45% -0.76%	1423.09 ms +0.93% -1.15%	1.32%
pngUploadProcessing	202.78 ms +4.2% -2.15%	199.42 ms +6.23% -3.32%	1.68%
largeJpegUploadProcessing	1415.59 ms +0.27% -0.44%	1407.31 ms +0.95% -0.21%	0.59%
multipleImageUploadProcessing	1582.59 ms +30.93% -1.23%	1564.78 ms +8.62% -0.51%	1.14%

post-editor

Metric	7624e29	trunk	% Change
serverResponse	527.37 ms +3.04% -4.85%	528.81 ms +2.88% -2.59%	-0.27%
firstPaint	228.57 ms +17.57% -6.76%	229.24 ms +14.46% -10.91%	-0.29%
domContentLoaded	1372.5 ms +1.95% -1.46%	1350.13 ms +1% -2.15%	1.66%
loaded	1373.8 ms +1.96% -1.46%	1351.4 ms +1.01% -2.14%	1.66%
firstContentfulPaint	464.3 ms +1.51% -2.47%	443.02 ms +2.9% -1.89%	4.8%
firstBlock	3813.15 ms +2.64% -1.7%	3698.03 ms +0.91% -0.72%	3.11%
type	16.78 ms +2.09% -4.65%	16.53 ms +5.57% -2.3%	1.51%
typeWithoutInspector	16.25 ms +6.83% -0.92%	19.49 ms +17.65% -10.67%	-16.62%
typeWithTopToolbar	19.37 ms +9.5% -0.98%	22.38 ms +5.63% -11.71%	-13.45%
typeContainer	10.41 ms +9.32% -14.41%	10.35 ms +6.47% -6.57%	0.58%
focus	83.13 ms +6.29% -1.83%	86.86 ms +25.69% -5.48%	-4.29%
firstFocus	178.6 ms +0% -0%	202.41 ms +0% -0%	-11.76%
selectAll	634.77 ms +5.52% -2.72%	643.75 ms +3.66% -2.08%	-1.39%
listViewOpen	75.59 ms +10.25% -5.24%	76.19 ms +21.97% -4.49%	-0.79%
inserterOpen	26.17 ms +14.79% -6.57%	26.62 ms +6.84% -13.75%	-1.69%
inserterHover	3.69 ms +9.49% -5.15%	4.61 ms +12.58% -11.5%	-19.96%
inserterSearch	8.9 ms +6.85% -1.24%	9.26 ms +16.2% -2.92%	-3.89%
loadPatterns	657.64 ms +0.93% -2%	677.98 ms +2.62% -7.23%	-3%
wpTotal	517.01 ms +3.05% -4.96%	518.87 ms +2.61% -2.69%	-0.36%
wpMemoryUsage	13.05 MB +0% -0%	13.02 MB +0% -0%	0.28%
wpDbQueries	54 +0% -1.85%	54 +0% -1.85%	0%

site-editor

Metric	7624e29	trunk	% Change
serverResponse	301.01 ms +5.45% -7.71%	314.61 ms +1.09% -1.73%	-4.32%
firstPaint	173.01 ms +9.81% -15.89%	173.8 ms +10.13% -11.24%	-0.45%
domContentLoaded	1045.83 ms +0.5% -1.35%	1042.78 ms +0.71% -0.76%	0.29%
loaded	1046.81 ms +0.51% -1.35%	1043.76 ms +0.7% -0.74%	0.29%
firstContentfulPaint	333.4 ms +4.27% -5.03%	330.57 ms +2.15% -2.71%	0.86%
firstBlock	3320.52 ms +0.41% -0.76%	3305.11 ms +0.32% -0.5%	0.47%
type	12.42 ms +2.5% -5.07%	11.71 ms +9.91% -4.53%	6.06%
navigate	62.46 ms +26.18% -1.02%	67.95 ms +21.78% -13.44%	-8.08%
loadPatterns	979.3 ms +1.99% -9.84%	988.45 ms +10.69% -2.55%	-0.93%
loadPages	1034.8 ms +2.46% -0.6%	1037.86 ms +2.05% -1.69%	-0.29%
wpTotal	292.88 ms +5.63% -7.94%	306.32 ms +1.01% -1.72%	-4.39%
wpMemoryUsage	12.06 MB +0% -0%	12.03 MB +0% -0%	0.3%
wpDbQueries	43.5 +1.15% -1.15%	44 +0% -0%	-1.14%

_{52a0d36 Run}

🏁 Flaky tests

Show the failures

Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

refuses the drop and uploads nothing in /test/e2e/specs/editor/various/single-file-placeholder-drop.spec.js, passed after 1 failed attempt.

Error: expect(received).toHaveLength(expected)

Expected length: 0
Received length: 2
Received array:  [{"_links": {"about": [{"href": "http://localhost:8889/wp-json/wp/v2/types/attachment"}], "author": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/users/1"}], "collection": [{"href": "http://localhost:8889/wp-json/wp/v2/media"}], "replies": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/comments?post=97"}], "self": [{"href": "http://localhost:8889/wp-json/wp/v2/media/97", "targetHints": {"allow": ["GET", "POST", "PUT", "PATCH", "DELETE"]}}]}, "alt_text": "", "author": 1, "caption": {"rendered": ""}, "class_list": ["post-97", "attachment", "type-attachment", "status-inherit", "hentry", "entry"], "comment_status": "open", "date": "2026-09-09T17:07:13", "date_gmt": "2026-09-09T17:07:13", "description": {"rendered": "<p class=\"attachment\"><a href='http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK-1.png'><img loading=\"lazy\" decoding=\"async\" width=\"10\" height=\"10\" src=\"http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK-1.png\" class=\"attachment-medium size-medium\" alt=\"\" style=\"width:100%;height:100%;max-width:10px;\" /></a></p>
"}, "featured_media": 0, "filename": "10x10_e2e_test_image_z9T8jK-1.png", "filesize": 80, "guid": {"rendered": "http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK-1.png"}, "id": 97, "link": "http://localhost:8889/10x10_e2e_test_image_z9t8jk-2/", "media_details": {"file": "2026/09/10x10_e2e_test_image_z9T8jK-1.png", "filesize": 80, "height": 10, "image_meta": {"alt": "", "aperture": "0", "camera": "", "caption": "", "copyright": "", "created_timestamp": "0", "credit": "", "focal_length": "0", "iso": "0", "keywords": [], "orientation": "0", "shutter_speed": "0", "title": ""}, "sizes": {}, "width": 10}, "media_type": "image", "meta": [], "mime_type": "image/png", "modified": "2026-09-09T17:07:13", "modified_gmt": "2026-09-09T17:07:13", "ping_status": "closed", "post": null, "slug": "10x10_e2e_test_image_z9t8jk-2", "source_url": "http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK-1.png", "status": "inherit", "template": "", "title": {"rendered": "10x10_e2e_test_image_z9T8jK"}, "type": "attachment"}, {"_links": {"about": [{"href": "http://localhost:8889/wp-json/wp/v2/types/attachment"}], "author": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/users/1"}], "collection": [{"href": "http://localhost:8889/wp-json/wp/v2/media"}], "replies": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/comments?post=93"}], "self": [{"href": "http://localhost:8889/wp-json/wp/v2/media/93", "targetHints": {"allow": ["GET", "POST", "PUT", "PATCH", "DELETE"]}}]}, "alt_text": "", "author": 1, "caption": {"rendered": ""}, "class_list": ["post-93", "attachment", "type-attachment", "status-inherit", "hentry", "entry"], "comment_status": "open", "date": "2026-09-09T17:06:53", "date_gmt": "2026-09-09T17:06:53", "description": {"rendered": "<p class=\"attachment\"><a href='http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK.png'><img loading=\"lazy\" decoding=\"async\" width=\"10\" height=\"10\" src=\"http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK.png\" class=\"attachment-medium size-medium\" alt=\"\" style=\"width:100%;height:100%;max-width:10px;\" /></a></p>
"}, "featured_media": 0, "filename": "10x10_e2e_test_image_z9T8jK.png", "filesize": 80, "guid": {"rendered": "http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK.png"}, "id": 93, "link": "http://localhost:8889/10x10_e2e_test_image_z9t8jk/", "media_details": {"file": "2026/09/10x10_e2e_test_image_z9T8jK.png", "filesize": 80, "height": 10, "image_meta": {"alt": "", "aperture": "0", "camera": "", "caption": "", "copyright": "", "created_timestamp": "0", "credit": "", "focal_length": "0", "iso": "0", "keywords": [], "orientation": "0", "shutter_speed": "0", "title": ""}, "sizes": {}, "width": 10}, "media_type": "image", "meta": [], "mime_type": "image/png", "modified": "2026-09-09T17:06:53", "modified_gmt": "2026-09-09T17:06:53", "ping_status": "closed", "post": null, "slug": "10x10_e2e_test_image_z9t8jk", "source_url": "http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK.png", "status": "inherit", "template": "", "title": {"rendered": "10x10_e2e_test_image_z9T8jK"}, "type": "attachment"}]
    at /home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/various/single-file-placeholder-drop.spec.js:71:45

_{52a0d36 Run}

[ciampo]

@WordPress/gutenberg-components @manzoorwanijk this PR was mostly a test to see if certain Vitest flags would result in faster test run, but it looks like they're mostly inconclusive