fix(storage): preserve IndexedDB Map and Set values by yury-s · Pull Request #42707 · microsoft/playwright

Yury Semikhatsky (yury-s) · 2026-09-14T16:11:49Z

Preserve Map and Set values, cycles, and shared references in IndexedDB snapshots, including Firefox cross-world wrappers.
Keep evaluate() serialization unchanged and add regression coverage.

Fixes: microsoft#42703 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Pavel Feldman (pavelfeldman) · 2026-09-14T16:29:37Z


+function isMap(obj: any): obj is Map<unknown, unknown> {
+  try {
+    return obj instanceof Map || Object.prototype.toString.call(obj) === '[object Map]';


we can be strict and drop [object Map]

instanceof Map fails for Firefox’s cross-world wrappers; removing the fallback breaks both IndexedDB roundtrip tests

Pavel Feldman (pavelfeldman) · 2026-09-14T16:30:38Z


      return { fallThrough: v };
-    });
+    }, { serializeMapAndSet: true });


expose this in evaluate?

Will do in a separate pr.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Devin Rousso (dcrousso) · 2026-09-14T17:31:30Z

+      const iterator = value.entries();
+      const next = new Map().entries().next;


is the idea here that we're trying to use our Map instead of whatever is in the object's realm? or are we just trying to avoid our code being observable by the page?

regardless, i think this maybe should be const iterator = Map.prototype.entries.call(value) to avoid it having overridden value.entries = function() { ... })

This to workaround Firefox not exposing iterator.next cross worlds. For storage state this code is running in the utility world, so we don't need to worry about entries override. I'll probably update it in the pr where this option become public on evaluate.

Devin Rousso (dcrousso) · 2026-09-14T17:31:41Z

+      const s: SerializedValue[] = [];
+      const id = ++visitorInfo.lastId;
+      visitorInfo.visited.set(value, id);
+      const iterator = value.values();


ditto with Set.prototype.values.call(value)

github-actions · 2026-09-14T17:50:41Z

Test results for "tests 1"

2 failed
❌ [firefox-library] › library/browsercontext-storage-state.spec.ts:453 › should work when service worker is intefering and the origin is not open @firefox-ubuntu-22.04-node20
❌ [playwright-test] › reporter.spec.ts:251 › created › should not have internal error when steps are finished after timeout @windows-latest-node22

7 flaky

⚠️ [chromium-library] › library/browsercontext-page-event.spec.ts:160 › should work with Shift-clicking `@chromium-ubuntu-22.04-arm-node20`
⚠️ [chromium-library] › library/chromium/chromium.spec.ts:213 › should intercept service worker requests (main and within) `@realtime-time-library-chromium-linux`
⚠️ [chromium-library] › library/video.spec.ts:699 › screencast › should capture full viewport on hidpi `@chromium-ubuntu-22.04-node24`
⚠️ [firefox-library] › library/browsercontext-cookies-third-party.spec.ts:257 › third party 'Partitioned;' cookies `@firefox-ubuntu-22.04-node20`
⚠️ [firefox-library] › library/browsercontext-cookies-third-party.spec.ts:470 › top level 'Partitioned;' cookie and same origin iframe `@firefox-ubuntu-22.04-node20`
⚠️ [firefox-page] › page/page-event-request.spec.ts:181 › should return response body when Cross-Origin-Opener-Policy is set `@firefox-ubuntu-22.04-node20`
⚠️ [playwright-test] › ui-mode-trace.spec.ts:189 › should show snapshots for steps `@windows-latest-node22`

51719 passed, 1247 skipped

Merge workflow run.

github-actions · 2026-09-14T17:53:46Z

Test results for "MCP"

8564 passed, 1446 skipped

Merge workflow run.

github-actions · 2026-09-14T17:56:23Z

Hi, I'm the Playwright bot and I triaged the CI failures on this PR.

🟢 Both failures are pre-existing — neither is caused by this PR. The Firefox storage-state failure is broken on main right now (fails 100% of Firefox runs, including push runs on 654654fc, da3553d3, 52a0e720), and the Windows reporter timeout is a known Windows-only flake that has timed out on main before.

Details

This PR only touches IndexedDB snapshot serialization: serializeAsCallArgument gains an opt-in extendedSerialization flag, and only storageScript.ts passes it. The evaluate() path is byte-for-byte unchanged, so nothing outside storage-state IndexedDB collection is reachable from the diff. The PR's own new tests all pass.

Pre-existing flake / infra

[firefox-library] › library/browsercontext-storage-state.spec.ts:453 › should work when service worker is intefering and the origin is not open — broken on Firefox independently of this PR. In the aggregated CI results this test is 0 passed / 8 failed on firefox-library while chromium-library (9/9) and webkit-library (8/8) are green. The failures include push runs on main at 654654fc, da3553d3 and 52a0e720, across firefox-ubuntu-22.04-node20, firefox-macos-15-large/xlarge, firefox-windows-latest and tracing-firefox. Same assertion everywhere — the service-worker-written fromServiceWorker localStorage entry leaks into the snapshot:
```
Error: expect(received).toEqual(expected) // deep equality
+ Object { "name": "fromServiceWorker", ... }
```
It has failed on Firefox since it landed in fix(chromium): bypass service workers on the storage state page #42664 (fix-42656), so this looks like the Firefox side of [Bug]: browserContext.storageState() runs third-party page JS and can fail when a visited origin has a service worker #42656 not being covered by that fix — worth a separate look, but not this PR's doing.
[playwright-test] › reporter.spec.ts:251 › created › should not have internal error when steps are finished after timeout — Windows-only timeout flake. The same test (merged variant of the same parametrized block, same file) has timed out at ~31s on windows-latest-node22 on push runs on main (04fb72b4, 77e4a17d) and on unrelated PRs docs(locator): drop type markup from ariaSnapshotJSON details #42136 and test: race between disabling interception and network request in chromium #42254. The test is simply close to the limit on that bot: mean 8.0s but p95 11.5s and max 36.1s on windows-latest-node22, versus a 7.9s max on every Linux/macOS bot, against a 30s timeout. It also timed out and was rescued on retry on an earlier commit of this PR (5cf3e2a6), and passed on all other bots.

Method: queried the aggregated CI results DB (2021 runs, topped up with update --lookback-days 3), grouping on (project_name, file, test_title).

_{Triaged by the Playwright bot - agent run}

fix(storage): preserve IndexedDB Map and Set values

bf792fb

Fixes: microsoft#42703 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Yury Semikhatsky (yury-s) requested review from Devin Rousso (dcrousso) and Pavel Feldman (pavelfeldman) September 14, 2026 16:12

chore(storage): use Map and Set type guards

ebb61bc

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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test(storage): simplify Map and Set roundtrip coverage

4cae111

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Yury Semikhatsky (yury-s) marked this pull request as ready for review September 14, 2026 16:28

Pavel Feldman (pavelfeldman) reviewed Sep 14, 2026

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Pavel Feldman (pavelfeldman) approved these changes Sep 14, 2026

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chore(storage): rename extended serialization option

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Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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Devin Rousso (dcrousso) approved these changes Sep 14, 2026

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Yury Semikhatsky (yury-s) merged commit d4ce80d into microsoft:main Sep 14, 2026
41 of 43 checks passed

Yury Semikhatsky (yury-s) deleted the fix-42703 branch September 14, 2026 17:43

This was referenced Sep 14, 2026

feat(evaluate): expose extended serialization for component testing #42709

Open

feat(ui-mode): update individual snapshots #42421

Open

test: fix click tests on android #42726

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JustasM (JustasMonkev) mentioned this pull request Sep 15, 2026

Review upstream browser failure paths on Playwright 1.63.0 JustasMonkev/mcp-accessibility-scanner#226

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fix(storage): preserve IndexedDB Map and Set values - #42707

fix(storage): preserve IndexedDB Map and Set values#42707
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		const iterator = value.entries();
		const next = new Map().entries().next;

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Test results for "tests 1"

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