Update to eslint v9 and eslint-config-scratch v12 #327

cwillisf · 2025-09-24T15:47:11Z

Proposed Changes

Update several dependencies:
- eslint: v8 to v9
- eslint-config-scratch: v9 to v12
- jest and ts-jest: v21 to v25
  - updated test snapshots (new jest doesn't record undefined properties, etc.)
- various support / plugin updates as well
Remove legacy eslint configuration files and create new, flat ones
Enable TypeScript & type-aware linting in scratch-gui
Fix tests broken by all these updates

Reason for Changes

Work around Bug: [indent] Maximum call stack size exceeded typescript-eslint/typescript-eslint#11455, which is currently causing Renovate lock file updates to fail
Keeping up to date is generally good

Test Coverage

Covered by existing tests, which have been updated to accommodate these changes.

Copilot

Pull Request Overview

This PR updates ESLint from version 8 to 9 and eslint-config-scratch from version 9 to 12, along with associated testing framework upgrades (Jest v21 to v25, ts-jest updates). The main change involves migrating from legacy ESLint configuration files to the new flat configuration format, while maintaining existing linting rules and behavior.

Migration from legacy .eslintrc.js files to new eslint.config.mjs flat configuration format
Update of core dependencies (ESLint v9, eslint-config-scratch v12, Jest v25)
Replacement of process.nextTick() with setTimeout() in tests due to Jest environment changes

Reviewed Changes

Copilot reviewed 79 out of 81 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/scratch-vm/eslint.config.mjs	New flat ESLint config replacing legacy .eslintrc.js files
packages/scratch-svg-renderer/eslint.config.mjs	New flat ESLint config with browser/node environment settings
packages/scratch-render/eslint.config.mjs	New flat ESLint config with playground-specific rule overrides
packages/scratch-gui/eslint.config.mjs	New comprehensive flat ESLint config with TypeScript support
packages/scratch-gui/test/unit/util/detect-locale.test.js	Refactored test to use Jest spies instead of Object.defineProperty
packages/scratch-gui/test/unit/util/vm-manager-hoc.test.jsx	Updated async test patterns for Jest v25 compatibility
packages/scratch-gui/src/lib/legacy-storage.ts	Added null check for projectHost property

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Copilot · 2025-09-24T15:47:48Z

packages/scratch-gui/src/lib/cloud-provider.js

+     * Set a timeout for a function to be called after a delay.
+     * @param {Function} fn The function to call after the delay.
+     * @param {number} time The delay time in milliseconds.


[nitpick] The JSDoc comment doesn't add value since it only restates what the method name and parameters already make clear. Consider removing this documentation or enhancing it to explain the specific context of why this timeout is being set (reconnection logic).

Suggested change

* Set a timeout for a function to be called after a delay.

* @param {Function} fn The function to call after the delay.

* @param {number} time The delay time in milliseconds.

* Schedule a reconnection attempt to the cloud data server after a websocket disconnect.

* This method manages the delay (with exponential backoff and jitter) before trying to reconnect,

* helping to avoid overwhelming the server with rapid reconnection attempts.

* @param {Function} fn The function to call after the delay (typically to reopen the connection).

* @param {number} time The delay time in milliseconds before attempting to reconnect.

I added a jsdoc comment specifically to make TS linting happy about the arg types

github-actions · 2025-09-24T15:57:58Z

Test report for scratch-svg-renderer

1 files ±0 60 suites ±0 0s ⏱️ ±0s
124 tests ±0 124 ✅ ±0 0 💤 ±0 0 ❌ ±0
276 runs ±0 275 ✅ ±0 1 💤 ±0 0 ❌ ±0

Results for commit e333f9c. ± Comparison against base commit 893c679.

♻️ This comment has been updated with latest results.

github-actions · 2025-09-24T16:00:08Z

Test report for scratch-render

1 files ±0 55 suites ±0 2s ⏱️ ±0s
209 tests ±0 209 ✅ ±0 0 💤 ±0 0 ❌ ±0
279 runs ±0 279 ✅ ±0 0 💤 ±0 0 ❌ ±0

Results for commit e333f9c. ± Comparison against base commit 893c679.

♻️ This comment has been updated with latest results.

github-actions · 2025-09-24T16:00:10Z

Test report for scratch-vm

1 files ±0 770 suites ±0 1m 5s ⏱️ ±0s
1 686 tests ±0 1 686 ✅ ±0 0 💤 ±0 0 ❌ ±0
4 891 runs ±0 4 861 ✅ ±0 30 💤 ±0 0 ❌ ±0

Results for commit e333f9c. ± Comparison against base commit 893c679.

♻️ This comment has been updated with latest results.

github-actions · 2025-09-24T16:01:31Z

Test report for scratch-gui

2 files ±0 62 suites ±0 9m 51s ⏱️ + 1m 3s
398 tests ±0 390 ✅ ±0 8 💤 ±0 0 ❌ ±0
416 runs ±0 408 ✅ ±0 8 💤 ±0 0 ❌ ±0

Results for commit e333f9c. ± Comparison against base commit 893c679.

♻️ This comment has been updated with latest results.

cwillisf · 2025-09-24T16:02:04Z

packages/scratch-gui/src/lib/legacy-storage.ts

+        if (!this.projectHost) {
+            return Promise.reject(new Error('Project host not set'));
+        }


Without this, TS said that passing this.projectHost to saveProjectToServer was invalid because it might be undefined.

cwillisf · 2025-09-24T16:07:31Z

packages/scratch-gui/test/unit/util/project-fetcher-hoc.test.jsx

        storage.load = originalLoad;
        // nextTick needed since storage.load is async, and onFetchedProject is called in its then()
-        process.nextTick(
+        setTimeout(


For some reason, process.nextTick wasn't delaying long enough. Waiting for 1ms seems to work. It wouldn't surprise me if this turns out to be flaky, though. These tests should ideally be event-driven (watch for a "load finished" event or something), but that'd be a larger change than I wanted to integrate into this PR.

cwillisf · 2025-09-24T16:09:49Z

packages/scratch-gui/package.json

-    "ts-jest": "21.2.4",
+    "ts-jest": "^25.5.1",


I was surprised to find that I had to update jest and ts-jest to get this all to work. I'm not sure exactly what the interaction was, but once I updated all the eslint-related things, jest started to fail with a parse error.

I figured it out, at least partially: [email protected] requires typescript@^2.4.1, but @typescript-eslint/eslint-plugin requires typescript>=4.8.4 <6.0.0. Npm "helpfully" resolves this by (among other things) providing a newer jest-cli to scratch-gui than the [email protected] that scratch-gui/package.json asks for. Bringing in a newer version of Jest introduces several new requirements that seem to be met by properly updating jest and ts-jest.

There are still a few holes in my understanding here, like why npm makes available a version of jest that doesn't match package.json instead of throwing an error, but I'm at least closer to understanding it 😅

cwillisf · 2025-09-24T16:12:00Z

packages/scratch-vm/src/extensions/scratch3_video_sensing/index.js

-    /**
-     * States the video sensing activity can be set to.
-     * @readonly
-     * @enum {string}
-     */
-    static get VideoState () {
-        return VideoState;
-    }
-


This was unused and causes a namespace collision for TS

KManolov3 · 2025-09-29T13:56:54Z

@cwillisf It's likely going to not be pretty, but should we try pointing this to https://github.com/scratchfoundation/scratch-editor/tree/UEPR-282-face-sensing, so that we are ready when it ends up being merged into develop in the next week or so?

cwillisf · 2025-09-29T14:30:07Z

@cwillisf It's likely going to not be pretty, but should we try pointing this to UEPR-282-face-sensing, so that we are ready when it ends up being merged into develop in the next week or so?

Probably a good idea... I'll see what it looks like.

KManolov3 · 2025-09-29T14:54:58Z

packages/scratch-gui/package.json

      "\\.(css|less)$": "<rootDir>/test/__mocks__/styleMock.js",
-      "editor-msgs(\\.js)?$": "<rootDir>/test/__mocks__/editor-msgs-mock.js"
+      "editor-msgs(\\.js)?$": "<rootDir>/test/__mocks__/editor-msgs-mock.js",
+      "^@scratch/scratch-svg-renderer$": "<rootDir>/../scratch-svg-renderer/src/"


Just curious - why did we end up needing this for svg-renderer, but not for e.g. -vm

KManolov3

That's quite a few changes! Let's wait for the face sensing release before merging this in develop, just to be sure.

Also remove eslint@^8 plugins/helpers. This commit by itself will break linting! Followup needed: - Upgrade to eslint@^9-compatible version of eslint-config-scratch - Migrate config files - Probably fix some legacy linting rules

The style rules for `scratch-gui` tests were very lax prior to the recent update to `eslint-config-scratch@^12`.

cwillisf · 2025-10-16T17:00:14Z

I just rebuilt this on top of the React 18 and Face Sensing changes. I also ran eslint --fix since these changes caused so many new lint warnings. Looks like Renovate did its thing while I had my back turned, but it should only take a little bit more merging before this is ready to go...

cwillisf requested review from KManolov3, adzhindzhi and Copilot September 24, 2025 15:47

cwillisf requested a review from a team as a code owner September 24, 2025 15:47

Copilot AI reviewed Sep 24, 2025

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cwillisf commented Sep 24, 2025

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KManolov3 reviewed Sep 29, 2025

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KManolov3 approved these changes Sep 29, 2025

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cwillisf added 13 commits October 15, 2025 07:47

chore(deps): update dependency eslint to v9

8848cd9

Also remove eslint@^8 plugins/helpers. This commit by itself will break linting! Followup needed: - Upgrade to eslint@^9-compatible version of eslint-config-scratch - Migrate config files - Probably fix some legacy linting rules

chore(deps): update scratch-svg-renderer to eslint-config-scratch@12

b68101d

chore(deps): update scratch-vm to eslint-config-scratch@12

f338321

chore(deps): update scratch-render to eslint-config-scratch@12

be57b1a

chore(deps): update scratch-gui to eslint-config-scratch@12

8d0b946

test: fix eslint errors in scratch-gui tests

30770e4

The style rules for `scratch-gui` tests were very lax prior to the recent update to `eslint-config-scratch@^12`.

chore(deps): upgrade {jest,ts-jest} to v25 to fix tests

5d7ca43

test: fix some scratch-gui unit tests

b1dcab2

test: fix detect-locale test with mock window

517717f

style: auto-fix lint issues in scratch-svg-renderer

24116e1

style: auto-fix lint issues in scratch-vm

c0b97ba

style: auto-fix lint issues in scratch-render

3795ddb

style: auto-fix lint issues in scratch-gui

e56dc93

cwillisf force-pushed the eslint-9-scratch-12 branch from 43c2233 to e56dc93 Compare October 16, 2025 16:56

Merge branch 'develop' into eslint-9-scratch-12

e333f9c

cwillisf added this pull request to the merge queue Oct 16, 2025

Merged via the queue into develop with commit 6662051 Oct 16, 2025
19 of 20 checks passed

github-actions bot locked and limited conversation to collaborators Oct 16, 2025

cwillisf deleted the eslint-9-scratch-12 branch October 16, 2025 18:11

-     * Set a timeout for a function to be called after a delay.
-     * @param {Function} fn The function to call after the delay.
-     * @param {number} time The delay time in milliseconds.
+     * Schedule a reconnection attempt to the cloud data server after a websocket disconnect.
+     * This method manages the delay (with exponential backoff and jitter) before trying to reconnect,
+     * helping to avoid overwhelming the server with rapid reconnection attempts.
+     * @param {Function} fn The function to call after the delay (typically to reopen the connection).
+     * @param {number} time The delay time in milliseconds before attempting to reconnect.

Update to eslint v9 and eslint-config-scratch v12 #327

Update to eslint v9 and eslint-config-scratch v12 #327

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