Chore: Add ESLint rule to enforce describe() titles match test file names (#16319)

.gitignore

@@ -2119,6 +2119,7 @@ packages/tools/checkIgnoredFiles.js
 packages/tools/checkLibPaths.test.js
 packages/tools/checkLibPaths.js
 packages/tools/convertThemesToCss.js
+packages/tools/eslint-rules/describeFilename.test.js
 packages/tools/fuzzer/ActionRunner.js
 packages/tools/fuzzer/Fuzzer.js
 packages/tools/fuzzer/cli.js
@@ -2196,8 +2197,8 @@ packages/tools/updateMarkdownDoc.js
 packages/tools/utils/discourse.test.js
 packages/tools/utils/discourse.js
 packages/tools/utils/loadSponsors.js
+packages/tools/utils/parsePluralLocalizationForm.test.js
 packages/tools/utils/parsePluralLocalizationForm.js
-packages/tools/utils/parsePlurallLocalizationForm.test.js
 packages/tools/utils/translation.js
 packages/tools/validateFilenames.js
 packages/tools/website/build.js

.ignore.eslint

@@ -83,6 +83,7 @@ packages/lib/welcomeAssets.js
 packages/editor/*/vendor/
 packages/plugins/**/api
 packages/plugins/**/dist
+packages/plugin-repo-cli/dist/
 packages/server/dist/
 packages/utils/dist/
 packages/transcribe/dist/
@@ -2144,6 +2145,7 @@ packages/tools/checkIgnoredFiles.js
 packages/tools/checkLibPaths.test.js
 packages/tools/checkLibPaths.js
 packages/tools/convertThemesToCss.js
+packages/tools/eslint-rules/describeFilename.test.js
 packages/tools/fuzzer/ActionRunner.js
 packages/tools/fuzzer/Fuzzer.js
 packages/tools/fuzzer/cli.js
@@ -2221,8 +2223,8 @@ packages/tools/updateMarkdownDoc.js
 packages/tools/utils/discourse.test.js
 packages/tools/utils/discourse.js
 packages/tools/utils/loadSponsors.js
+packages/tools/utils/parsePluralLocalizationForm.test.js
 packages/tools/utils/parsePluralLocalizationForm.js
-packages/tools/utils/parsePlurallLocalizationForm.test.js
 packages/tools/utils/translation.js
 packages/tools/validateFilenames.js
 packages/tools/website/build.js

eslint.config.js

@@ -14,6 +14,8 @@ const github = require('eslint-plugin-github');
 const { fixupPluginRules, includeIgnoreFile } = require('@eslint/compat');
 const js = require('@eslint/js');
 
+const joplin = require('./packages/tools/eslint-rules');
+
 const { join } = require('path');
 
 // As of ESLint v9, .eslintignore is no longer supported and the presence of
@@ -246,6 +248,7 @@ module.exports = defineConfig([{
 		promise,
 		jest,
 		github: fixupPluginRules(github),
+		joplin,
 	},
 }, {
 	files: [
@@ -257,6 +260,12 @@ module.exports = defineConfig([{
 	rules: {
 		'no-console': 'off',
 	},
+}, {
+	files: ['**/*.test.ts', '**/*.test.tsx', '**/*.test.js', '**/*.test.jsx'],
+
+	rules: {
+		'joplin/describe-filename': ['error'],
+	},
 }, {
 	// .jsx files should be linted with the default rules
 	files: ['**/*.jsx'],

packages/app-desktop/gui/NoteEditor/NoteBody/WhiteboardEditor/useCheckboxToggle.test.ts

@@ -5,7 +5,7 @@ import { flipNthCheckbox } from './useCheckboxToggle';
 // `flipNthCheckbox` must count exactly the same subset so the Nth rendered
 // checkbox maps to the Nth source-text checkbox.
 
-describe('flipNthCheckbox', () => {
+describe('useCheckboxToggle', () => {
 	test('flips an unchecked box to checked', () => {
 		expect(flipNthCheckbox('- [ ] todo', 0)).toBe('- [x] todo');
 	});

packages/app-desktop/gui/NoteList/utils/UseAutoScroll.test.ts

@@ -8,7 +8,7 @@ type Props = {
 	makeItemIndexVisible: (index: number)=> void;
 };
 
-describe('useAutoScroll', () => {
+describe('UseAutoScroll', () => {
 
 	test('scrolls to the note when a new note is selected', () => {
 		const makeItemIndexVisible = jest.fn();

packages/app-desktop/gui/PromptDialog.test.ts

@@ -1,6 +1,6 @@
 import PromptDialog from './PromptDialog';
 
-describe('PromptDialog Escape key handling', () => {
+describe('PromptDialog', () => {
 
 	const setupKeyHandler = (inputType: string, menuIsOpened: boolean) => {
 		const onCloseMock = jest.fn();

packages/app-desktop/gui/WindowCommandsAndDialogs/commands/showSpellCheckerMenu.test.ts

@@ -12,7 +12,7 @@ jest.mock('../../../services/bridge', () => ({
 	}),
 }));
 
-describe('mapStateToTitle', () => {
+describe('showSpellCheckerMenu', () => {
 
 	test('should return null if spellchecker.enabled is false', () => {
 

packages/app-desktop/utils/checkForUpdatesUtils.test.ts

@@ -1,7 +1,7 @@
 import { extractVersionInfo, Release, Platform, Architecture, GitHubRelease, handleReleaseResponseError } from './checkForUpdatesUtils';
 import { releases1, releases2 } from './checkForUpdatesUtilsTestData';
 
-describe('checkForUpdates', () => {
+describe('checkForUpdatesUtils', () => {
 
 	it('should extract version info and return the non-arm64 version', async () => {
 		const testCases: [GitHubRelease[], Platform, Architecture, boolean, Release][] = [

packages/app-mobile/components/screens/Note/Note.test.tsx

@@ -158,7 +158,7 @@ const setupNoteWithPanes = async (panes: string[], noteTitle = 'Test note') => {
 	return renderResult;
 };
 
-describe('screens/Note', () => {
+describe('screens/Note/Note', () => {
 	beforeEach(async () => {
 		await setupDatabaseAndSynchronizer(1);
 		await setupDatabaseAndSynchronizer(0);

packages/app-mobile/components/screens/SearchScreen/SearchResults.test.tsx

@@ -31,7 +31,7 @@ const WrappedSearchResults: React.FC<WrapperProps> = props => (
 	</TestProviderStack>
 );
 
-describe('SearchResult', () => {
+describe('SearchResults', () => {
 	beforeEach(async () => {
 		await setupDatabaseAndSynchronizer(1);
 		await switchClient(1);

packages/app-mobile/components/screens/ShareManager/index.test.tsx

@@ -29,7 +29,7 @@ const ShareManagerWrapper: React.FC<WrapperProps> = props => {
 	);
 };
 
-describe('ShareManager', () => {
+describe('ShareManager/index', () => {
 	beforeEach(async () => {
 		await setupDatabaseAndSynchronizer(1);
 		await switchClient(1);

packages/app-mobile/contentScripts/imageEditorBundle/contentScript/index.test.ts

@@ -48,7 +48,7 @@ const createEditorWithCallbacks = (callbacks: Partial<MainProcessApi>) => {
 	return createJsDrawEditor(allCallbacks, toolbarState, locale, localizations, editorOptions);
 };
 
-describe('imageEditor/contentScript/index', () => {
+describe('contentScript/index', () => {
 	it('should trigger autosave callback every few minutes', async () => {
 		let calledAutosaveCount = 0;
 

packages/editor/CodeMirror/extensions/links/followLinkTooltipExtension.test.ts

@@ -3,7 +3,7 @@ import createTestEditor from '../../testing/createTestEditor';
 import followLinkTooltip from './followLinkTooltipExtension';
 import { EditorSelection } from '@codemirror/state';
 
-describe('followLinkTooltip', () => {
+describe('followLinkTooltipExtension', () => {
 	it('should show a clickable tooltip for a URL link', async () => {
 		const doc = '[link](http://example.com/)';
 		const onOpenLink = jest.fn();

packages/editor/CodeMirror/extensions/markdownDecorationExtension.test.ts

@@ -4,7 +4,7 @@ import decoratorExtension from './markdownDecorationExtension';
 
 jest.retryTimes(2);
 
-describe('decoratorExtension', () => {
+describe('markdownDecorationExtension', () => {
 	it('should highlight code blocks within tables', async () => {
 		// Regression test for https://github.com/laurent22/joplin/issues/9477
 		const editorText = `

packages/editor/CodeMirror/extensions/markdownFrontMatterExtension.test.ts

@@ -9,7 +9,7 @@ const createEditorState = async (initialText: string, expectedTags: string[]): P
 	return (await createTestEditor(initialText, EditorSelection.cursor(0), expectedTags)).state;
 };
 
-describe('MarkdownFrontMatterExtension', () => {
+describe('markdownFrontMatterExtension', () => {
 
 	jest.retryTimes(2);
 

packages/editor/CodeMirror/extensions/markdownHighlightExtension.test.ts

@@ -9,7 +9,7 @@ const createEditorState = async (initialText: string, expectedTags: string[]): P
 };
 
 
-describe('MarkdownHighlightExtension', () => {
+describe('markdownHighlightExtension', () => {
 	jest.retryTimes(2);
 
 	it.each([

packages/editor/CodeMirror/extensions/markdownMathExtension.test.ts

@@ -9,7 +9,7 @@ const createEditorState = async (initialText: string, expectedTags: string[]): P
 	return (await createTestEditor(initialText, EditorSelection.cursor(0), expectedTags)).state;
 };
 
-describe('MarkdownMathExtension', () => {
+describe('markdownMathExtension', () => {
 
 	jest.retryTimes(2);
 

packages/editor/ProseMirror/commands/commands.test.ts

@@ -12,7 +12,7 @@ const moveCursorToEnd = (editor: EditorView) => {
 	selectDocumentEnd(editor.state, editor.dispatch, editor);
 };
 
-describe('ProseMirror/commands', () => {
+describe('commands', () => {
 	test('textBold should toggle bold formatting', () => {
 		const editor = createTestEditor({ html: '<p>Test</p>' });
 

packages/editor/ProseMirror/plugins/joplinEditablePlugin/showCreateEditablePrompt.test.ts

@@ -30,7 +30,7 @@ const findEditorDialog = () => {
 	};
 };
 
-describe('showCreateEditorPrompt', () => {
+describe('showCreateEditablePrompt', () => {
 	beforeEach(() => {
 		jest.useFakeTimers();
 		document.body.replaceChildren();

packages/lib/htmlUtils2.test.ts

@@ -1,6 +1,6 @@
 import htmlUtils from './htmlUtils';
 
-describe('htmlUtils', () => {
+describe('htmlUtils2', () => {
 
 
 

packages/lib/import-enex-html-gen.test.ts

@@ -44,7 +44,7 @@ const compareOutputToExpected = (options: CompareOutputOptions) => {
 	}));
 };
 
-describe('EnexToHtml', () => {
+describe('import-enex-html-gen', () => {
 	beforeEach(async () => {
 		await setupDatabaseAndSynchronizer(1);
 		await switchClient(1);

packages/lib/markdownUtils.test.ts

@@ -1,6 +1,6 @@
 import markdownUtils from './markdownUtils';
 
-describe('Should detect list items', () => {
+describe('markdownUtils', () => {
 	test('should detect `- lorem ipsum` as list item ', () => {
 		expect(markdownUtils.isListItem('- lorem ipsum')).toBe(true);
 	});

packages/lib/markdownUtils2.test.ts

@@ -2,7 +2,7 @@
 
 import markdownUtils from './markdownUtils';
 
-describe('markdownUtils', () => {
+describe('markdownUtils2', () => {
 
 
 

packages/lib/models/dateTimeFormats.test.ts

@@ -1,7 +1,7 @@
 import Setting from '../models/Setting';
 import time from '../time';
 
-describe('dateFormats', () => {
+describe('dateTimeFormats', () => {
 
 
 

packages/lib/registry.test.ts

@@ -5,7 +5,7 @@ const sync = {
 	start: jest.fn().mockReturnValue({}),
 };
 
-describe('Registry', () => {
+describe('registry', () => {
 	let originalSyncTarget: typeof reg.syncTarget;
 
 	beforeAll(() => {

packages/lib/services/CommandService.test.ts

@@ -46,7 +46,7 @@ const registerSecondaryRuntime = (service: CommandService, commandName: string,
 	return service.registerRuntime(commandName, runtime, true);
 };
 
-describe('services_CommandService', () => {
+describe('CommandService', () => {
 
 	beforeEach(async () => {
 		KeymapService.destroyInstance();

packages/lib/services/KeymapService.test.ts

@@ -4,7 +4,7 @@ import KeymapService, { KeymapItem } from '../services/KeymapService';
 const keymapService = KeymapService.instance();
 keymapService.initialize([]);
 
-describe('services_KeymapService', () => {
+describe('KeymapService', () => {
 	describe('validateAccelerator', () => {
 		it('should identify valid Accelerators', () => {
 			const testCases = {

packages/lib/services/KvStore.test.ts

@@ -7,7 +7,7 @@ function setupStore() {
 	return store;
 }
 
-describe('services_KvStore', () => {
+describe('KvStore', () => {
 
 	beforeEach(async () => {
 		await setupDatabaseAndSynchronizer(1);

packages/lib/services/ai/OnnxRuntime.test.ts

@@ -5,7 +5,7 @@ import shim from '../../shim';
 // goal of this test is to catch packaging/native-binary breakage early, the
 // same way SqliteVec.test does for sqlite-vec.
 
-describe('onnxruntime-node', () => {
+describe('OnnxRuntime', () => {
 
 	it('is reachable via the shim', () => {
 		const ort = shim.onnxRuntime();

packages/lib/services/conflict/diffNotes.test.ts

@@ -1,6 +1,6 @@
 import { autoMerge } from './diffNotes';
 
-describe('autoMerge', () => {
+describe('diffNotes', () => {
 
 	test('should auto-apply non-conflicting changes on different lines', () => {
 		const base = 'one\ntwo\nthree';

packages/lib/services/e2ee/EncryptionService.test.ts

@@ -9,7 +9,7 @@ import { setEncryptionEnabled } from '../synchronizer/syncInfoUtils';
 
 let service: EncryptionService = null;
 
-describe('services_EncryptionService', () => {
+describe('EncryptionService', () => {
 
 	beforeEach(async () => {
 		await setupDatabaseAndSynchronizer(1);

packages/lib/services/e2ee/ppk/ppk.test.ts

@@ -3,7 +3,7 @@ import { PublicKeyAlgorithm } from '../types';
 import { decryptPrivateKey, ppkDecryptMasterKeyContent, ppkGenerateMasterKey, ppkPasswordIsValid, mkReencryptFromPasswordToPublicKey, mkReencryptFromPublicKeyToPassword, generateKeyPairWithAlgorithm, supportsPpkAlgorithm } from './ppk';
 import { runIntegrationTests } from './ppkTestUtils';
 
-describe('e2ee/ppk', () => {
+describe('ppk', () => {
 
 	beforeEach(async () => {
 		await setupDatabaseAndSynchronizer(1);

packages/lib/services/interop/InteropService.test.ts

@@ -87,7 +87,7 @@ function memoryExportModule() {
 const oneNoteSimpleXpsPath = () => `${supportDir}/onenote/simple-xps.one`;
 const skipByDefault = process.env.IS_CONTINUOUS_INTEGRATION ? it : it.skip;
 
-describe('services_InteropService', () => {
+describe('InteropService', () => {
 
 	const setupOneNoteDomParser = () => {
 		const jsdom = new JSDOM('<div></div>');

packages/lib/services/plugins/utils/isCompatible/index.test.ts

@@ -1,7 +1,7 @@
 import { AppType } from '../../../../models/Setting';
 import isCompatible from '../isCompatible';
 
-describe('isCompatible', () => {
+describe('isCompatible/index', () => {
 	test.each([
 		// Should support the case where no platform is provided
 		{

packages/lib/services/search/SearchEngine.test.ts

@@ -56,7 +56,7 @@ let engine: SearchEngine = null;
 // 	return scores;
 // };
 
-describe('services/SearchEngine', () => {
+describe('SearchEngine', () => {
 
 	beforeEach(async () => {
 		await setupDatabaseAndSynchronizer(1);

packages/lib/services/search/SearchFilter.test.ts

@@ -23,7 +23,7 @@ const dateStringToTimestamp = (dateString: string) => {
 	return localTimestamp.getTime() + localTimestamp.getTimezoneOffset() * minutesToMilliseconds;
 };
 
-describe('services_SearchFilter', () => {
+describe('SearchFilter', () => {
 	beforeEach(async () => {
 		await setupDatabaseAndSynchronizer(1);
 		await switchClient(1);

packages/lib/services/search/filterParser.test.ts

@@ -6,7 +6,7 @@ const makeTerm = (name: string, value: string, negated: boolean, quoted = false,
 	return { name, value, negated };
 };
 
-describe('filterParser should be correct filter for keyword', () => {
+describe('filterParser', () => {
 	it('title', () => {
 		const searchString = 'title: something';
 		expect(filterParser(searchString)).toContainEqual(makeTerm('title', 'something', false));

packages/lib/services/synchronizer/synchronizer_MigrationHandler.test.ts

@@ -143,7 +143,7 @@ async function testMigrationE2EE(migrationVersion: number, maxSyncVersion: numbe
 
 let previousSyncTargetName = '';
 
-describe('MigrationHandler', () => {
+describe('synchronizer_MigrationHandler', () => {
 
 	beforeEach(async () => {
 		// Note that, for undocumented reasons, the timeout argument passed

packages/lib/services/trash/index.test.ts

@@ -2,7 +2,7 @@ import { getDisplayParentId, getTrashFolderId } from '.';
 import { ModelType } from '../../BaseModel';
 import Folder from '../../models/Folder';
 
-describe('services/trash', () => {
+describe('trash/index', () => {
 
 	test.each([
 		[

packages/lib/utils/webDAVUtils.test.ts

@@ -1,7 +1,7 @@
 import checkProviderIsSupported from './webDAVUtils';
 import Setting from '../models/Setting';
 
-describe('checkProviderIsSupported', () => {
+describe('webDAVUtils', () => {
 	describe('when no unsupported provider is already configured', () => {
 		beforeAll(() => {
 			Setting.setValue('sync.allowUnsupportedProviders', 0);

packages/pdf-viewer/pdfSource.test.ts

@@ -20,7 +20,7 @@ function loadFile(filePath: string) {
 	});
 }
 
-describe('pdfData', () => {
+describe('pdfSource', () => {
 
 	test('should have correct page count', async () => {
 		const file = await loadFile(pdfFilePath1);

packages/renderer/MdToHtml/rules/katex.test.ts

@@ -18,7 +18,7 @@ const createMarkdownIt = (strict?: unknown) => {
 	return md;
 };
 
-describe('katex rule', () => {
+describe('katex', () => {
 
 	let warnSpy: jest.SpiedFunction<typeof console.warn>;
 

packages/server/src/models/ChangeModel/ChangeModel.test.ts

@@ -32,7 +32,7 @@ const clearChanges = () => {
 	return truncateTables(db(), ['changes', 'changes_2']);
 };
 
-describe('ChangeModel/index', () => {
+describe('ChangeModel', () => {
 
 	beforeAll(async () => {
 		await beforeAllDb('ChangeModel');

packages/server/src/models/UserItemModels.test.ts

@@ -1,6 +1,6 @@
 import { beforeAllDb, afterAllTests, beforeEachDb, models } from '../utils/testing/testUtils';
 
-describe('UserItemModel', () => {
+describe('UserItemModels', () => {
 
 	beforeAll(async () => {
 		await beforeAllDb('UserItemModel');

packages/server/src/models/utils/user.test.ts

@@ -1,6 +1,6 @@
 import { isHashedPassword } from '../../utils/auth';
 
-describe('isHashedPassword', () => {
+describe('user', () => {
 
 	// cSpell:disable
 	it('should be true if password starts with $2a$10', () => {

packages/server/src/routes/api/ping.test.ts

@@ -1,7 +1,7 @@
 import routeHandler from '../../middleware/routeHandler';
 import { beforeAllDb, afterAllTests, beforeEachDb, koaAppContext } from '../../utils/testing/testUtils';
 
-describe('api_ping', () => {
+describe('ping', () => {
 
 	beforeAll(async () => {
 		await beforeAllDb('api_ping');

packages/server/src/routes/api/transcribe.test.ts

@@ -36,7 +36,7 @@ const fetchSpyOn = (response: FetchResponse) => {
 	);
 };
 
-describe('api_transcribe', () => {
+describe('transcribe', () => {
 
 	beforeAll(async () => {
 		await beforeAllDb('api_transcribe', {

packages/server/src/routes/index/changes.test.ts

@@ -1,6 +1,6 @@
 // Disabled for now
 
-describe('index_changes', () => {
+describe('changes', () => {
 
 	it('should pass', () => {
 		expect(true).toBe(true);

packages/server/src/routes/index/items.test.ts

@@ -3,7 +3,7 @@ import { execRequest, execRequestC } from '../../utils/testing/apiUtils';
 import { Uuid } from '../../services/database/types';
 import { makeNoteSerializedBody } from '../../utils/testing/serializedItems';
 
-describe('index_items', () => {
+describe('index/items', () => {
 
 	beforeAll(async () => {
 		await beforeAllDb('index_items');

packages/server/src/routes/index/login.test.ts

@@ -40,7 +40,7 @@ async function doLoginWithMFA(email: string, password: string, mfaCode: string,
 	return context;
 }
 
-describe('index_login', () => {
+describe('login', () => {
 
 	beforeAll(async () => {
 		await beforeAllDb('index_login', {

packages/server/src/routes/index/logout.test.ts

@@ -2,7 +2,7 @@ import routeHandler from '../../middleware/routeHandler';
 import { cookieGet } from '../../utils/cookies';
 import { beforeAllDb, afterAllTests, beforeEachDb, koaAppContext, models, createUserAndSession } from '../../utils/testing/testUtils';
 
-describe('index_logout', () => {
+describe('logout', () => {
 
 	beforeAll(async () => {
 		await beforeAllDb('index_logout');

packages/server/src/routes/index/notifications.test.ts

@@ -3,7 +3,7 @@ import routeHandler from '../../middleware/routeHandler';
 import { NotificationKey } from '../../models/NotificationModel';
 import { beforeAllDb, afterAllTests, beforeEachDb, koaAppContext, models, createUserAndSession } from '../../utils/testing/testUtils';
 
-describe('index_notification', () => {
+describe('notifications', () => {
 
 	beforeAll(async () => {
 		await beforeAllDb('index_notification');

packages/server/src/routes/index/signup.test.ts

@@ -8,7 +8,7 @@ import { beforeAllDb, afterAllTests, beforeEachDb, models } from '../../utils/te
 import { uuidgen } from '@joplin/lib/uuid';
 import { FormUser } from './signup';
 
-describe('index_signup', () => {
+describe('signup', () => {
 
 	beforeAll(async () => {
 		await beforeAllDb('index_signup');

packages/server/src/utils/saml.test.ts

@@ -5,7 +5,7 @@ import { getLoginRequest } from './saml';
 import { afterAllTests, beforeAllDb, beforeEachDb } from './testing/testUtils';
 import { SamlRelayState } from './types';
 
-describe('getLoginRequest', () => {
+describe('saml', () => {
 	let dir: string;
 
 	beforeAll(async () => {

packages/tools/eslint-rules/describeFilename.js

@@ -0,0 +1,90 @@
+const { basename, sep } = require('path');
+
+// Enforces that the top-level `describe()` title in a test file matches the
+// file name, or a path suffix ending with that file name. For example, for
+// `packages/lib/models/Tag.test.ts`, valid titles are "Tag", "models/Tag" or
+// "lib/models/Tag".
+
+const testFileSuffix = /\.test$/;
+
+const filePathTitles = (filePath) => {
+	const parts = filePath.split(sep);
+	parts[parts.length - 1] = basename(parts[parts.length - 1]).replace(/\.[^.]+$/, '').replace(testFileSuffix, '');
+
+	const output = [];
+	for (let i = parts.length - 1; i >= 0; i--) {
+		output.push(parts.slice(i).join('/'));
+	}
+	return output;
+};
+
+// `describe.each` builds its title from the test data, so a printf placeholder
+// such as "%j", or a "$variable" tag, may follow the file name.
+const eachTitle = (title, allowed) => {
+	const match = /^(.*?)\s*[([]?[%$]/.exec(title);
+	return !!match && allowed.includes(match[1]);
+};
+
+const isDescribe = (callee) => {
+	if (callee.type === 'Identifier') return callee.name === 'describe';
+	// describe.each(...)(...) - the callee is itself a call expression, and
+	// describe.each`...`(...) - a tagged template expression.
+	if (callee.type === 'CallExpression') return isDescribe(callee.callee);
+	if (callee.type === 'TaggedTemplateExpression') return isDescribe(callee.tag);
+	if (callee.type === 'MemberExpression' && !callee.computed) {
+		return isDescribe(callee.object);
+	}
+	return false;
+};
+
+const isEach = (callee) => {
+	if (callee.type === 'CallExpression') return isEach(callee.callee);
+	if (callee.type === 'TaggedTemplateExpression') return isEach(callee.tag);
+	if (callee.type === 'MemberExpression' && !callee.computed) {
+		return callee.property.name === 'each' || isEach(callee.object);
+	}
+	return false;
+};
+
+module.exports = {
+	meta: {
+		type: 'problem',
+		docs: {
+			description: 'Require the top-level describe() title to match the test file name or a path suffix to it',
+		},
+		schema: [],
+		messages: {
+			mismatch: 'The describe() title should be "{{expected}}", or a longer path suffix to the file (eg. "{{alternative}}").',
+			dynamic: 'The describe() title should be a string literal matching the file name ("{{expected}}").',
+		},
+	},
+
+	create(context) {
+		const filePath = context.filename ?? context.getFilename();
+		if (!/\.test\.[jt]sx?$/.test(filePath)) return {};
+
+		const allowed = filePathTitles(filePath);
+		const data = { expected: allowed[0], alternative: allowed[1] ?? allowed[0] };
+
+		return {
+			// Only top-level describe() calls - nested ones are inside a function
+			// body so their ancestor chain includes a CallExpression.
+			'Program > ExpressionStatement > CallExpression'(node) {
+				if (!isDescribe(node.callee)) return;
+
+				const [title] = node.arguments;
+				if (!title) return;
+
+				if (title.type !== 'Literal' || typeof title.value !== 'string') {
+					context.report({ node: title, messageId: 'dynamic', data });
+					return;
+				}
+
+				if (allowed.includes(title.value)) return;
+				if (isEach(node.callee) && eachTitle(title.value, allowed)) return;
+
+				context.report({ node: title, messageId: 'mismatch', data });
+			},
+		};
+	},
+};

packages/tools/eslint-rules/describeFilename.test.ts

@@ -0,0 +1,49 @@
+import { RuleTester } from 'eslint';
+
+const rule = require('./describeFilename');
+
+// RuleTester emits its own describe/test blocks, so it must be called at the
+// top level rather than from inside a test().
+const ruleTester = new RuleTester({
+	languageOptions: { ecmaVersion: 2021, sourceType: 'module' },
+});
+
+const filename = '/repo/packages/lib/models/Tag.test.ts';
+
+ruleTester.run('describe-filename', rule, {
+	valid: [
+		// The file name, or any path suffix ending with it.
+		{ code: 'describe(\'Tag\', () => {});', filename },
+		{ code: 'describe(\'models/Tag\', () => {});', filename },
+		{ code: 'describe(\'lib/models/Tag\', () => {});', filename },
+
+		// Supported describe variants.
+		{ code: 'describe.skip(\'Tag\', () => {});', filename },
+		{ code: 'describe.only(\'Tag\', () => {});', filename },
+
+		// describe.each builds the title from the test data, so a printf
+		// placeholder or a $tag may follow the file name.
+		{ code: 'describe.each([1])(\'Tag (%j)\', () => {});', filename },
+		{ code: 'describe.each([1])(\'Tag $name\', () => {});', filename },
+		{ code: 'describe.each`\\na\\n${1}\\n`(\'Tag $a\', () => {});', filename },
+
+		// Nested describes are unrestricted.
+		{ code: 'describe(\'Tag\', () => { describe(\'anything\', () => {}); });', filename },
+
+		// Non-test files are not checked.
+		{ code: 'describe(\'anything\', () => {});', filename: '/repo/packages/lib/models/Tag.ts' },
+	],
+
+	invalid: [
+		{ code: 'describe(\'something\', () => {});', filename, errors: [{ messageId: 'mismatch' }] },
+		{ code: 'describe(\'Tag rule\', () => {});', filename, errors: [{ messageId: 'mismatch' }] },
+		{ code: 'describe(\'services/Tag\', () => {});', filename, errors: [{ messageId: 'mismatch' }] },
+		{ code: 'describe.skip(\'nope\', () => {});', filename, errors: [{ messageId: 'mismatch' }] },
+		{ code: 'describe.each([1])(\'nope (%j)\', () => {});', filename, errors: [{ messageId: 'mismatch' }] },
+		{ code: 'describe.each`\\na\\n${1}\\n`(\'nope $a\', () => {});', filename, errors: [{ messageId: 'mismatch' }] },
+
+		// Dynamic titles cannot be validated, so they are reported.
+		{ code: 'describe(`Tag ${x}`, () => {});', filename, errors: [{ messageId: 'dynamic' }] },
+		{ code: 'describe(title, () => {});', filename, errors: [{ messageId: 'dynamic' }] },
+	],
+});

packages/tools/eslint-rules/index.js

@@ -0,0 +1,5 @@
+module.exports = {
+	rules: {
+		'describe-filename': require('./describeFilename'),
+	},
+};

packages/utils/html.test.ts

@@ -1,7 +1,7 @@
 import { extractUrls } from './html';
 import { Link } from './types';
 
-describe('htmlUtils', () => {
+describe('html', () => {
 
 	test.each([
 		[