chore: enable a bunch more lint rules (jestjs#14794)

.eslintrc.cjs

@@ -35,13 +35,19 @@ module.exports = {
     'plugin:eslint-comments/recommended',
     'plugin:prettier/recommended',
     'plugin:unicorn/recommended',
+    'plugin:promise/recommended',
   ],
   globals: {
     console: 'readonly',
   },
   overrides: [
     {
-      extends: ['plugin:@typescript-eslint/strict', 'plugin:import/typescript'],
+      extends: [
+        'plugin:@typescript-eslint/eslint-recommended',
+        'plugin:@typescript-eslint/strict',
+        'plugin:@typescript-eslint/stylistic',
+        'plugin:import/typescript',
+      ],
       files: ['*.ts', '*.tsx'],
       plugins: ['@typescript-eslint/eslint-plugin', 'local'],
       rules: {
@@ -59,6 +65,7 @@ module.exports = {
         ],
         '@typescript-eslint/prefer-ts-expect-error': 'error',
         '@typescript-eslint/no-var-requires': 'off',
+        '@typescript-eslint/consistent-indexed-object-style': 'off',
         // TS verifies these
         'consistent-return': 'off',
         'no-dupe-class-members': 'off',
@@ -68,10 +75,7 @@ module.exports = {
         '@typescript-eslint/no-explicit-any': 'off',
         '@typescript-eslint/no-non-null-assertion': 'off',
         '@typescript-eslint/no-invalid-void-type': 'off',
-
-        // TODO: part of "stylistic" rules, remove explicit activation when that lands
-        '@typescript-eslint/no-empty-function': 'error',
-        '@typescript-eslint/no-empty-interface': 'error',
+        '@typescript-eslint/consistent-type-definitions': 'off',
 
         // not needed to be enforced for TS
         'import/namespace': 'off',
@@ -326,6 +330,7 @@ module.exports = {
       rules: {
         '@typescript-eslint/ban-ts-comment': 'off',
         '@typescript-eslint/no-empty-function': 'off',
+        '@typescript-eslint/class-literal-property-style': 'off',
       },
     },
     {
@@ -427,6 +432,12 @@ module.exports = {
         'unicorn/no-static-only-class': 'off',
       },
     },
+    {
+      files: '**/*.mjs',
+      rules: {
+        'unicorn/prefer-top-level-await': 'error',
+      },
+    },
   ],
   parser: '@typescript-eslint/parser',
   parserOptions: {
@@ -617,6 +628,11 @@ module.exports = {
     'prefer-arrow-callback': ['error', {allowNamedFunctions: true}],
     'prefer-const': 'error',
     'prefer-template': 'error',
+
+    'promise/always-return': 'off',
+    'promise/catch-or-return': 'off',
+    'promise/no-callback-in-promise': 'off',
+
     quotes: [
       'error',
       'single',
@@ -655,10 +671,8 @@ module.exports = {
     'unicorn/prefer-event-target': 'off',
     'unicorn/prefer-switch': 'off',
     'unicorn/prefer-ternary': 'off',
-    'unicorn/switch-case-braces': 'off',
-
-    // TODO: enable for `.mjs` files
     'unicorn/prefer-top-level-await': 'off',
+    'unicorn/switch-case-braces': 'off',
 
     // TODO: decide whether or not we want these
     'unicorn/filename-case': 'off',

e2e/jasmine-async/__tests__/concurrent-parallel-failure.test.js

@@ -8,7 +8,7 @@
 'use strict';
 
 it.concurrent('Good Test', async () => {
-  await new Promise(r => setTimeout(r, 100));
+  await new Promise(resolve => setTimeout(resolve, 100));
 });
 
 it.concurrent('Bad Test', async () => {

e2e/snapshot-concurrent/__tests__/works.test.js

@@ -7,7 +7,7 @@
  */
 'use strict';
 
-const sleep = ms => new Promise(r => setTimeout(r, ms));
+const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
 
 describe('A', () => {
   it.concurrent('a', async () => {

package.json

@@ -41,6 +41,7 @@
     "eslint-plugin-local": "link:./.eslintplugin",
     "eslint-plugin-markdown": "^3.0.0",
     "eslint-plugin-prettier": "^5.0.0",
+    "eslint-plugin-promise": "^6.1.1",
     "eslint-plugin-unicorn": "^50.0.0",
     "execa": "^5.0.0",
     "find-process": "^1.4.1",

packages/babel-plugin-jest-hoist/src/index.ts

@@ -133,7 +133,7 @@ FUNCTIONS.mock = args => {
       );
     }
 
-    const ids: Set<NodePath<Identifier>> = new Set();
+    const ids = new Set<NodePath<Identifier>>();
     const parentScope = moduleFactory.parentPath.scope;
     // @ts-expect-error: ReferencedIdentifier and denylist are not known on visitors
     moduleFactory.traverse(IDVisitor, {ids});

packages/expect-utils/src/jasmineUtils.ts

@@ -76,13 +76,8 @@ function eq(
   }
 
   const testerContext: TesterContext = {equals};
-  for (let i = 0; i < customTesters.length; i++) {
-    const customTesterResult = customTesters[i].call(
-      testerContext,
-      a,
-      b,
-      customTesters,
-    );
+  for (const item of customTesters) {
+    const customTesterResult = item.call(testerContext, a, b, customTesters);
     if (customTesterResult !== undefined) {
       return customTesterResult;
     }

packages/expect/src/index.ts

@@ -203,7 +203,7 @@ const makeResolveMatcher =
           )}\n\n` +
           'Received promise rejected instead of resolved\n' +
           `Rejected to value: ${matcherUtils.printReceived(reason)}`;
-        return Promise.reject(outerErr);
+        throw outerErr;
       },
     );
   };
@@ -254,7 +254,7 @@ const makeRejectMatcher =
           )}\n\n` +
           'Received promise resolved instead of rejected\n' +
           `Resolved to value: ${matcherUtils.printReceived(result)}`;
-        return Promise.reject(outerErr);
+        throw outerErr;
       },
       reason =>
         makeThrowingMatcher(matcher, isNot, 'rejects', reason, innerErr).apply(

packages/expect/src/types.ts

@@ -98,11 +98,10 @@ export interface BaseExpect {
   setState(state: Partial<MatcherState>): void;
 }
 
-export type Expect = {
-  <T = unknown>(
-    actual: T,
-  ): Matchers<void, T> & Inverse<Matchers<void, T>> & PromiseMatchers<T>;
-} & BaseExpect &
+export type Expect = (<T = unknown>(
+  actual: T,
+) => Matchers<void, T> & Inverse<Matchers<void, T>> & PromiseMatchers<T>) &
+  BaseExpect &
   AsymmetricMatchers &
   Inverse<Omit<AsymmetricMatchers, 'any' | 'anything'>>;
 

packages/jest-core/src/__tests__/collectHandles.test.js

@@ -113,8 +113,8 @@ describe('collectHandles', () => {
     const server = http.createServer((_, response) => response.end('ok'));
 
     // Start and stop server.
-    await new Promise(r => server.listen(0, r));
-    await new Promise(r => server.close(r));
+    await new Promise(resolve => server.listen(0, resolve));
+    await new Promise(resolve => server.close(resolve));
 
     const openHandles = await handleCollector();
     expect(openHandles).toHaveLength(0);
@@ -130,11 +130,13 @@ describe('collectHandles', () => {
     // creates a long-lived `TCPSERVERWRAP` resource. We want to make sure we
     // capture that long-lived resource.
     const server = new http.Server();
-    await new Promise(r => server.listen({host: 'localhost', port: 0}, r));
+    await new Promise(resolve =>
+      server.listen({host: 'localhost', port: 0}, resolve),
+    );
 
     const openHandles = await handleCollector();
 
-    await new Promise(r => server.close(r));
+    await new Promise(resolve => server.close(resolve));
 
     expect(openHandles).toContainEqual(
       expect.objectContaining({message: 'TCPSERVERWRAP'}),

packages/jest-core/src/__tests__/watch.test.js

@@ -88,7 +88,7 @@ const regularUpdateGlobalConfig = require('../lib/updateGlobalConfig').default;
 const updateGlobalConfig = jest.fn(regularUpdateGlobalConfig);
 jest.doMock('../lib/updateGlobalConfig', () => updateGlobalConfig);
 
-const nextTick = () => new Promise(res => process.nextTick(res));
+const nextTick = () => new Promise(resolve => process.nextTick(resolve));
 
 beforeAll(() => {
   jest.spyOn(process, 'on').mockImplementation(() => {});
@@ -771,7 +771,9 @@ describe('Watch mode flows', () => {
 
   it('prevents Jest from handling keys when active and returns control when end is called', async () => {
     let resolveShowPrompt;
-    const run = jest.fn(() => new Promise(res => (resolveShowPrompt = res)));
+    const run = jest.fn(
+      () => new Promise(resolve => (resolveShowPrompt = resolve)),
+    );
     const pluginPath = `${__dirname}/__fixtures__/plugin_path_1`;
     jest.doMock(
       pluginPath,

packages/jest-core/src/__tests__/watchFilenamePatternMode.test.js

@@ -68,7 +68,7 @@ jest.doMock(
 
 const watch = require('../watch').default;
 
-const nextTick = () => new Promise(res => process.nextTick(res));
+const nextTick = () => new Promise(resolve => process.nextTick(resolve));
 
 const globalConfig = {
   rootDir: '',

packages/jest-core/src/plugins/TestNamePattern.ts

@@ -41,7 +41,7 @@ class TestNamePatternPlugin extends BaseWatchPlugin {
     globalConfig: Config.GlobalConfig,
     updateConfigAndRun: UpdateConfigCallback,
   ): Promise<void> {
-    return new Promise((res, rej) => {
+    return new Promise((resolve, reject) => {
       const testNamePatternPrompt = new TestNamePatternPrompt(
         this._stdout,
         this._prompt,
@@ -50,9 +50,9 @@ class TestNamePatternPlugin extends BaseWatchPlugin {
       testNamePatternPrompt.run(
         (value: string) => {
           updateConfigAndRun({mode: 'watch', testNamePattern: value});
-          res();
+          resolve();
         },
-        rej,
+        reject,
         {
           header: activeFilters(globalConfig),
         },

packages/jest-core/src/plugins/TestPathPattern.ts

@@ -41,7 +41,7 @@ class TestPathPatternPlugin extends BaseWatchPlugin {
     globalConfig: Config.GlobalConfig,
     updateConfigAndRun: UpdateConfigCallback,
   ): Promise<void> {
-    return new Promise((res, rej) => {
+    return new Promise((resolve, reject) => {
       const testPathPatternPrompt = new TestPathPatternPrompt(
         this._stdout,
         this._prompt,
@@ -50,9 +50,9 @@ class TestPathPatternPlugin extends BaseWatchPlugin {
       testPathPatternPrompt.run(
         (value: string) => {
           updateConfigAndRun({mode: 'watch', testPathPatterns: [value]});
-          res();
+          resolve();
         },
-        rej,
+        reject,
         {
           header: activeFilters(globalConfig),
         },

packages/jest-core/src/plugins/UpdateSnapshotsInteractive.ts

@@ -67,7 +67,7 @@ class UpdateSnapshotInteractivePlugin extends BaseWatchPlugin {
     updateConfigAndRun: Function,
   ): Promise<void> {
     if (this._failedSnapshotTestAssertions.length > 0) {
-      return new Promise(res => {
+      return new Promise(resolve => {
         this._snapshotInteractiveMode.run(
           this._failedSnapshotTestAssertions,
           (assertion, shouldUpdateSnapshot) => {
@@ -79,7 +79,7 @@ class UpdateSnapshotInteractivePlugin extends BaseWatchPlugin {
               updateSnapshot: shouldUpdateSnapshot ? 'all' : 'none',
             });
             if (!this._snapshotInteractiveMode.isActive()) {
-              res();
+              resolve();
             }
           },
         );

packages/jest-docblock/src/index.ts

@@ -27,8 +27,9 @@ export function extract(contents: string): string {
 }
 
 export function strip(contents: string): string {
-  const match = contents.match(docblockRe);
-  return match && match[0] ? contents.slice(match[0].length) : contents;
+  const matchResult = contents.match(docblockRe);
+  const match = matchResult?.[0];
+  return match == null ? contents : contents.slice(match.length);
 }
 
 export function parse(docblock: string): Pragmas {

packages/jest-haste-map/src/blacklist.ts

@@ -15,7 +15,7 @@
 //
 // Feel free to add any extensions that cannot be a Haste module.
 
-const extensions: Set<string> = new Set([
+const extensions = new Set<string>([
   // JSONs are never haste modules, except for "package.json", which is handled.
   '.json',
 

packages/jest-jasmine2/src/jasmine/CallTracker.ts

@@ -71,9 +71,9 @@ class CallTracker {
     };
 
     this.allArgs = function () {
-      const callArgs = [];
-      for (let i = 0; i < calls.length; i++) {
-        callArgs.push(calls[i].args);
+      const callArgs: Array<unknown> = [];
+      for (const call of calls) {
+        callArgs.push(call.args);
       }
 
       return callArgs;

packages/jest-jasmine2/src/jasmine/ReportDispatcher.ts

@@ -56,8 +56,7 @@ export default class ReportDispatcher implements Reporter {
   constructor(methods: Array<keyof Reporter>) {
     const dispatchedMethods = methods || [];
 
-    for (let i = 0; i < dispatchedMethods.length; i++) {
-      const method = dispatchedMethods[i];
+    for (const method of dispatchedMethods) {
       this[method] = (function (m) {
         return function () {
           dispatch(m, arguments);
@@ -86,8 +85,7 @@ export default class ReportDispatcher implements Reporter {
       if (reporters.length === 0 && fallbackReporter !== null) {
         reporters.push(fallbackReporter);
       }
-      for (let i = 0; i < reporters.length; i++) {
-        const reporter = reporters[i];
+      for (const reporter of reporters) {
         if (reporter[method]) {
           // @ts-expect-error: wrong context
           reporter[method].apply(reporter, args);

packages/jest-jasmine2/src/jasmine/Suite.ts

@@ -190,8 +190,7 @@ export default class Suite {
       };
       this.result.failedExpectations.push(expectationResultFactory(data));
     } else {
-      for (let i = 0; i < this.children.length; i++) {
-        const child = this.children[i];
+      for (const child of this.children) {
         child.onException.apply(child, args);
       }
     }
@@ -205,8 +204,7 @@ export default class Suite {
         throw new ExpectationFailed();
       }
     } else {
-      for (let i = 0; i < this.children.length; i++) {
-        const child = this.children[i];
+      for (const child of this.children) {
         try {
           child.addExpectationResult.apply(child, args);
         } catch {

packages/jest-matcher-utils/src/deepCyclicCopyReplaceable.ts

@@ -36,7 +36,7 @@ const isMap = (value: any): value is Map<unknown, unknown> =>
 
 export default function deepCyclicCopyReplaceable<T>(
   value: T,
-  cycles: WeakMap<any, any> = new WeakMap(),
+  cycles = new WeakMap<any, any>(),
 ): T {
   if (typeof value !== 'object' || value === null) {
     return value;

packages/jest-mock/__typetests__/Mocked.test.ts

@@ -101,9 +101,7 @@ interface SomeFunctionObject {
   one: {
     (oneA: number, oneB?: boolean): boolean;
     more: {
-      time: {
-        (time: number): void;
-      };
+      time: (time: number) => void;
     };
   };
 }