typescript-eslint · JoshuaKGoldberg · Apr 11, 2025 · Feb 3, 2025 · Feb 3, 2025 · Feb 4, 2025
diff --git a/.gitignore b/.gitignore
@@ -99,3 +99,6 @@ packages/**/.yarn
 
 .nx/cache
 .nx/workspace-data
+
+# Vitest type tests
+tsconfig*.vitest-temp.json
diff --git a/eslint.config.mjs b/eslint.config.mjs
@@ -35,6 +35,7 @@ const vitestFiles = [
   'packages/visitor-keys/tests/**/*.test.{ts,tsx,cts,mts}',
   'packages/parser/tests/lib/**/*.test.{ts,tsx,cts,mts}',
   'packages/parser/tests/test-utils/**/*.{ts,tsx,cts,mts}',
+  'packages/utils/tests/**/*.test?(-d).{ts,tsx,cts,mts}',
 ];
 
 export default tseslint.config(

diff --git a/knip.ts b/knip.ts
@@ -86,7 +86,6 @@ export default {
     },
     'packages/utils': {
       ignore: [
-        'tests/**/*.type-test.ts',
         'typings/eslint.d.ts',
         'typings/eslint-community-eslint-utils.d.ts',
       ],

diff --git a/packages/utils/jest.config.js b/packages/utils/jest.config.js
diff --git a/packages/utils/package.json b/packages/utils/package.json
@@ -57,10 +57,10 @@
     "build": "tsc -b tsconfig.build.json",
     "postbuild": "downlevel-dts dist _ts4.3/dist --to=4.3",
     "clean": "tsc -b tsconfig.build.json --clean",
-    "postclean": "rimraf dist && rimraf _ts3.4 && rimraf _ts4.3 && rimraf coverage",
+    "postclean": "rimraf dist/ _ts4.3/ coverage/",
     "format": "prettier --write \"./**/*.{ts,mts,cts,tsx,js,mjs,cjs,jsx,json,md,css}\" --ignore-path ../../.prettierignore",
     "lint": "npx nx lint",
-    "test": "jest",
+    "test": "vitest --run --config=$INIT_CWD/vitest.config.mts",
     "check-types": "npx nx typecheck"
   },
   "dependencies": {
@@ -74,11 +74,12 @@
     "typescript": ">=4.8.4 <5.9.0"
   },
   "devDependencies": {
+    "@vitest/coverage-v8": "^3.1.1",
     "downlevel-dts": "*",
-    "jest": "29.7.0",
     "prettier": "^3.2.5",
     "rimraf": "*",
-    "typescript": "*"
+    "typescript": "*",
+    "vitest": "^3.1.1"
   },
   "funding": {
     "type": "opencollective",

diff --git a/packages/utils/project.json b/packages/utils/project.json
@@ -1,12 +1,17 @@
 {
   "name": "utils",
   "$schema": "../../node_modules/nx/schemas/project-schema.json",
-  "type": "library",
-  "implicitDependencies": [],
+  "projectType": "library",
+  "root": "packages/utils",
+  "sourceRoot": "packages/utils/src",
   "targets": {
     "lint": {
       "executor": "@nx/eslint:lint",
       "outputs": ["{options.outputFile}"]
+    },
+    "test": {
+      "executor": "@nx/vite:test",
+      "dependsOn": ["^build", "typecheck"]
     }
   }
 }
diff --git a/packages/utils/tests/eslint-utils/RuleCreator.test.ts b/packages/utils/tests/eslint-utils/RuleCreator.test.ts
@@ -1,14 +1,14 @@
 import { ESLintUtils } from '../../src';
 
-describe('RuleCreator', () => {
+describe(ESLintUtils.RuleCreator, () => {
   interface TestDocs {
     recommended?: 'yes';
   }
 
   const createRule = ESLintUtils.RuleCreator<TestDocs>(name => `test/${name}`);
 
   it('createRule should be a function', () => {
-    expect(typeof createRule).toBe('function');
+    expect(createRule).toBeTypeOf('function');
   });
 
   it('should create rule correctly', () => {

diff --git a/packages/utils/tests/eslint-utils/applyDefault.test.ts b/packages/utils/tests/eslint-utils/applyDefault.test.ts
@@ -1,6 +1,6 @@
 import { ESLintUtils } from '../../src';
 
-describe('applyDefault', () => {
+describe(ESLintUtils.applyDefault, () => {
   it('returns a clone of the default if no options given', () => {
     const defaults = [{ prop: 'setting' }];
     const user = null;

diff --git a/packages/utils/tests/eslint-utils/deepMerge.test.ts b/packages/utils/tests/eslint-utils/deepMerge.test.ts
@@ -1,6 +1,6 @@
 import { ESLintUtils } from '../../src';
 
-describe('deepMerge', () => {
+describe(ESLintUtils.deepMerge, () => {
   it('creates a brand new object', () => {
     const a = {};
     const b = {};

diff --git a/packages/utils/tests/eslint-utils/getParserServices.test.ts b/packages/utils/tests/eslint-utils/getParserServices.test.ts
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- wild and wacky testing */
 import type * as ts from 'typescript';
 
 import type { ParserServices, TSESLint, TSESTree } from '../../src';
@@ -38,14 +37,14 @@ const unknownParserErrorRegex = (parser?: string): RegExp =>
 Note: detected a parser other than @typescript-eslint/parser. Make sure the parser is configured to forward "parserOptions.project" to @typescript-eslint/parser.`,
   );
 
-describe('getParserServices', () => {
+describe(ESLintUtils.getParserServices, () => {
   it('throws a standard error with the parser when parserOptions.esTreeNodeToTSNodeMap is missing and the parser is typescript-eslint', () => {
     const context = createMockRuleContext({
       sourceCode: {
         ...defaults.sourceCode,
         parserServices: {
           ...defaults.sourceCode.parserServices,
-          esTreeNodeToTSNodeMap: undefined as any,
+          esTreeNodeToTSNodeMap: undefined,
         },
       },
     });
@@ -69,7 +68,7 @@ describe('getParserServices', () => {
         ...defaults.sourceCode,
         parserServices: {
           ...defaults.sourceCode.parserServices,
-          esTreeNodeToTSNodeMap: undefined as any,
+          esTreeNodeToTSNodeMap: undefined,
         },
       },
     });
@@ -87,7 +86,7 @@ describe('getParserServices', () => {
         ...defaults.sourceCode,
         parserServices: {
           ...defaults.sourceCode.parserServices,
-          esTreeNodeToTSNodeMap: undefined as any,
+          esTreeNodeToTSNodeMap: undefined,
         },
       },
     });
@@ -107,7 +106,7 @@ describe('getParserServices', () => {
         ...defaults.sourceCode,
         parserServices: {
           ...defaults.sourceCode.parserServices,
-          esTreeNodeToTSNodeMap: undefined as any,
+          esTreeNodeToTSNodeMap: undefined,
         },
       },
     });
@@ -124,7 +123,7 @@ describe('getParserServices', () => {
         ...defaults.sourceCode,
         parserServices: {
           ...defaults.sourceCode.parserServices,
-          esTreeNodeToTSNodeMap: undefined as any,
+          esTreeNodeToTSNodeMap: undefined,
         },
       },
     });
@@ -139,7 +138,7 @@ describe('getParserServices', () => {
         ...defaults.sourceCode,
         parserServices: {
           ...defaults.sourceCode.parserServices,
-          tsNodeToESTreeNodeMap: undefined as any,
+          tsNodeToESTreeNodeMap: undefined,
         },
       },
     });
@@ -155,7 +154,7 @@ describe('getParserServices', () => {
         ...defaults.sourceCode,
         parserServices: {
           ...defaults.sourceCode.parserServices,
-          program: undefined as any,
+          program: undefined,
         },
       },
     });
@@ -171,7 +170,7 @@ describe('getParserServices', () => {
         ...defaults.sourceCode,
         parserServices: {
           ...defaults.sourceCode.parserServices,
-          program: undefined as any,
+          program: undefined,
         },
       },
     });

diff --git a/packages/utils/tests/eslint-utils/nullThrows.test.ts b/packages/utils/tests/eslint-utils/nullThrows.test.ts
@@ -1,6 +1,6 @@
 import { nullThrows, NullThrowsReasons } from '../../src/eslint-utils';
 
-describe('nullThrows', () => {
+describe(nullThrows, () => {
   it('returns a falsy value when it exists', () => {
     const value = 0;
 

diff --git a/packages/utils/tests/eslint-utils/parserSeemsToBeTSESLint.test.ts b/packages/utils/tests/eslint-utils/parserSeemsToBeTSESLint.test.ts
@@ -1,7 +1,7 @@
 import { parserSeemsToBeTSESLint } from '../../src/eslint-utils/parserSeemsToBeTSESLint';
 
-describe('parserSeemsToBeTSESLint', () => {
-  test.each([
+describe(parserSeemsToBeTSESLint, () => {
+  test.for([
     [undefined, false],
     ['espree', false],
     ['local.js', false],
@@ -20,7 +20,7 @@ describe('parserSeemsToBeTSESLint', () => {
     ['/path/to/typescript-eslint/packages/parser/index.js', true],
     ['/path/to/@typescript-eslint/packages/parser/dist/index.js', true],
     ['/path/to/@typescript-eslint/packages/parser/index.js', true],
-  ])('%s', (parserPath, expected) => {
+  ] as const)('%s', ([parserPath, expected], { expect }) => {
     expect(parserSeemsToBeTSESLint(parserPath)).toBe(expected);
   });
 });
diff --git a/...s/utils/tests/ts-eslint/Rule.type-test.ts → ...ages/utils/tests/ts-eslint/Rule.test-d.ts b/...s/utils/tests/ts-eslint/Rule.type-test.ts → ...ages/utils/tests/ts-eslint/Rule.test-d.ts
@@ -14,8 +14,6 @@ type AllSelectors =
   | `${TSESTree.AST_NODE_TYPES}:exit`
   | `${TSESTree.AST_NODE_TYPES}`;
 
-type ExpectNever<T extends never> = T;
-
 type SelectorsWithWrongNodeType = {
   [K in TSESTree.AST_NODE_TYPES]: Parameters<
     NonNullable<RuleListener[K]>
@@ -25,13 +23,11 @@ type SelectorsWithWrongNodeType = {
       : K
     : K;
 }[TSESTree.AST_NODE_TYPES];
-type _test_rule_listener_selectors_have_correct_node_types =
-  ExpectNever<SelectorsWithWrongNodeType>;
 
-type ExtraSelectors = Exclude<RuleListenerSelectors, AllSelectors>;
-type _test_rule_listener_does_not_define_extra_selectors =
-  ExpectNever<ExtraSelectors>;
+test('type tests', () => {
+  expectTypeOf<SelectorsWithWrongNodeType>().toBeNever();
+
+  expectTypeOf<RuleListenerSelectors>().exclude<AllSelectors>().toBeNever();
 
-type MissingSelectors = Exclude<AllSelectors, RuleListenerSelectors>;
-type _test_rule_listener_has_selectors_for_all_node_types =
-  ExpectNever<MissingSelectors>;
+  expectTypeOf<AllSelectors>().exclude<RuleListenerSelectors>().toBeNever();
+});
diff --git a/packages/utils/tsconfig.build.json b/packages/utils/tsconfig.build.json
@@ -10,7 +10,7 @@
   },
   "include": ["src/**/*.ts", "typings"],
   "exclude": [
-    "jest.config.js",
+    "vitest.config.mts",
     "src/**/*.spec.ts",
     "src/**/*.test.ts",
     "**/fixtures/**"

diff --git a/packages/utils/tsconfig.spec.json b/packages/utils/tsconfig.spec.json
@@ -3,10 +3,12 @@
   "compilerOptions": {
     "outDir": "../../dist/out-tsc/packages/utils",
     "module": "NodeNext",
-    "types": ["jest", "node"]
+    "resolveJsonModule": true,
+    "types": ["node", "vitest/globals", "vitest/importMeta"]
   },
   "include": [
-    "jest.config.js",
+    "vitest.config.mts",
+    "package.json",
     "src/**/*.test.ts",
     "src/**/*.spec.ts",
     "src/**/*.d.ts",
@@ -16,6 +18,9 @@
   "references": [
     {
       "path": "./tsconfig.build.json"
+    },
+    {
+      "path": "../../tsconfig.spec.json"
     }
   ]
 }
diff --git a/packages/utils/vitest.config.mts b/packages/utils/vitest.config.mts
@@ -0,0 +1,26 @@
+import * as path from 'node:path';
+import { defineProject, mergeConfig } from 'vitest/config';
+
+import { vitestBaseConfig } from '../../vitest.config.base.mjs';
+import packageJson from './package.json' with { type: 'json' };
+
+const vitestConfig = mergeConfig(
+  vitestBaseConfig,
+
+  defineProject({
+    root: import.meta.dirname,
+
+    test: {
+      dir: path.join(import.meta.dirname, 'tests'),
+      name: packageJson.name.replace('@typescript-eslint/', ''),
+      root: import.meta.dirname,
+
+      typecheck: {
+        enabled: true,
+        tsconfig: path.join(import.meta.dirname, 'tsconfig.spec.json'),
+      },
+    },
+  }),
+);
+
+export default vitestConfig;
diff --git a/yarn.lock b/yarn.lock
@@ -6312,11 +6312,12 @@ __metadata:
     "@typescript-eslint/scope-manager": 8.29.1
     "@typescript-eslint/types": 8.29.1
     "@typescript-eslint/typescript-estree": 8.29.1
+    "@vitest/coverage-v8": ^3.1.1
     downlevel-dts: "*"
-    jest: 29.7.0
     prettier: ^3.2.5
     rimraf: "*"
     typescript: "*"
+    vitest: ^3.1.1
   peerDependencies:
     eslint: ^8.57.0 || ^9.0.0
     typescript: ">=4.8.4 <5.9.0"