feat: add new package rule-tester

.eslintignore

@@ -12,3 +12,6 @@ packages/types/src/generated/**/*.ts
 
 # Playground types downloaded from the web
 packages/website/src/vendor
+
+# see the file header in eslint-base.test.js for more info
+packages/rule-tester/tests/eslint-base

.prettierignore

@@ -18,3 +18,6 @@ CHANGELOG.md
 
 packages/website/.docusaurus
 packages/website/build
+
+# see the file header in eslint-base.test.js for more info
+packages/rule-tester/tests/eslint-base

.vscode/launch.json

@@ -72,6 +72,42 @@
         "${workspaceFolder}/packages/scope-manager/dist/index.js",
       ],
     },
+    {
+      "type": "node",
+      "request": "launch",
+      "name": "Run currently opened rule-tester test",
+      "cwd": "${workspaceFolder}/packages/rule-tester/",
+      "program": "${workspaceFolder}/node_modules/jest/bin/jest.js",
+      "args": [
+        "--runInBand",
+        "--no-cache",
+        "--no-coverage",
+        "${fileBasename}"
+      ],
+      "sourceMaps": true,
+      "console": "integratedTerminal",
+      "internalConsoleOptions": "neverOpen",
+      "skipFiles": [
+        "${workspaceFolder}/packages/utils/src/index.ts",
+        "${workspaceFolder}/packages/utils/dist/index.js",
+        "${workspaceFolder}/packages/utils/src/ts-estree.ts",
+        "${workspaceFolder}/packages/utils/dist/ts-estree.js",
+        "${workspaceFolder}/packages/type-utils/src/ts-estree.ts",
+        "${workspaceFolder}/packages/type-utils/dist/ts-estree.js",
+        "${workspaceFolder}/packages/parser/src/index.ts",
+        "${workspaceFolder}/packages/parser/dist/index.js",
+        "${workspaceFolder}/packages/rule-tester/src/index.ts",
+        "${workspaceFolder}/packages/rule-tester/dist/index.js",
+        "${workspaceFolder}/packages/typescript-estree/src/index.ts",
+        "${workspaceFolder}/packages/typescript-estree/dist/index.js",
+        "${workspaceFolder}/packages/types/src/index.ts",
+        "${workspaceFolder}/packages/types/dist/index.js",
+        "${workspaceFolder}/packages/visitor-keys/src/index.ts",
+        "${workspaceFolder}/packages/visitor-keys/dist/index.js",
+        "${workspaceFolder}/packages/scope-manager/dist/index.js",
+        "${workspaceFolder}/packages/scope-manager/dist/index.js",
+      ],
+    },
     {
       "type": "node",
       "request": "launch",

packages/eslint-plugin-tslint/package.json

@@ -46,8 +46,7 @@
     "typecheck": "tsc -p tsconfig.json --noEmit"
   },
   "dependencies": {
-    "@typescript-eslint/utils": "5.56.0",
-    "lodash": "^4.17.21"
+    "@typescript-eslint/utils": "5.56.0"
   },
   "peerDependencies": {
     "eslint": "^7.0.0 || ^8.0.0",

packages/eslint-plugin-tslint/src/rules/config.ts

@@ -1,10 +1,27 @@
 import { ESLintUtils } from '@typescript-eslint/utils';
-import memoize from 'lodash/memoize';
 import type { RuleSeverity } from 'tslint';
 import { Configuration } from 'tslint';
 
 import { CustomLinter } from '../custom-linter';
 
+function memoize<T extends (...args: never[]) => unknown>(
+  func: T,
+  resolver: (...args: Parameters<T>) => string,
+): T {
+  const cache = new Map<string, ReturnType<T>>();
+  const memoized = function (...args) {
+    const key = resolver(...(args as Parameters<T>));
+
+    if (cache.has(key)) {
+      return cache.get(key)!;
+    }
+    const result = func(...args);
+    cache.set(key, result as ReturnType<T>);
+    return result;
+  } as T;
+  return memoized;
+}
+
 // note - cannot migrate this to an import statement because it will make TSC copy the package.json to the dist folder
 // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
 const version: string = require('../../package.json');

packages/rule-tester/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2019 typescript-eslint and other contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

packages/rule-tester/README.md

@@ -0,0 +1,8 @@
+# `@typescript-eslint/rule-tester`
+
+> Tooling to test ESLint rules
+
+[![NPM Version](https://img.shields.io/npm/v/@typescript-eslint/rule-tester.svg?style=flat-square)](https://www.npmjs.com/package/@typescript-eslint/rule-tester)
+[![NPM Downloads](https://img.shields.io/npm/dm/@typescript-eslint/rule-tester.svg?style=flat-square)](https://www.npmjs.com/package/@typescript-eslint/rule-tester)
+
+👉 See **https://typescript-eslint.io/architecture/rule-tester** for documentation on this package.

packages/rule-tester/jest.config.js

@@ -0,0 +1,7 @@
+'use strict';
+
+// @ts-check
+/** @type {import('@jest/types').Config.InitialOptions} */
+module.exports = {
+  ...require('../../jest.config.base.js'),
+};

packages/rule-tester/package.json

@@ -0,0 +1,79 @@
+{
+  "name": "@typescript-eslint/rule-tester",
+  "version": "5.56.0",
+  "description": "Tooling to test ESLint rules",
+  "files": [
+    "dist",
+    "_ts4.2",
+    "README.md",
+    "LICENSE"
+  ],
+  "type": "commonjs",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "default": "./dist/index.js"
+    },
+    "./package.json": "./package.json"
+  },
+  "engines": {
+    "node": "^14.18.0 || ^16.0.0 || >=18.0.0"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/typescript-eslint/typescript-eslint.git",
+    "directory": "packages/rule-tester"
+  },
+  "bugs": {
+    "url": "https://github.com/typescript-eslint/typescript-eslint/issues"
+  },
+  "license": "MIT",
+  "keywords": [
+    "eslint",
+    "typescript",
+    "estree"
+  ],
+  "scripts": {
+    "build": "tsc -b tsconfig.build.json",
+    "postbuild": "downlevel-dts dist _ts4.2/dist --to=4.2",
+    "clean": "tsc -b tsconfig.build.json --clean",
+    "postclean": "rimraf dist && rimraf _ts3.4 && rimraf coverage",
+    "format": "prettier --write \"./**/*.{ts,mts,cts,tsx,js,mjs,cjs,jsx,json,md,css}\" --ignore-path ../../.prettierignore",
+    "lint": "nx lint",
+    "pretest-eslint-base": "tsc -b tsconfig.build.json",
+    "test-eslint-base": "mocha --require source-map-support/register ./tests/eslint-base/eslint-base.test.js",
+    "test": "jest --coverage",
+    "typecheck": "tsc -p tsconfig.json --noEmit"
+  },
+  "//": "NOTE - AJV is out-of-date, but it's intentionally synced with ESLint - https://github.com/eslint/eslint/blob/ad9dd6a933fd098a0d99c6a9aa059850535c23ee/package.json#L70",
+  "dependencies": {
+    "@typescript-eslint/typescript-estree": "5.56.0",
+    "@typescript-eslint/utils": "5.56.0",
+    "lodash.merge": "4.6.2",
+    "semver": "^7.3.7",
+    "ajv": "^6.10.0"
+  },
+  "peerDependencies": {
+    "@eslint/eslintrc": ">=2",
+    "eslint": ">=8"
+  },
+  "devDependencies": {
+    "@typescript-eslint/parser": "5.56.0",
+    "@types/lodash.merge": "4.6.7",
+    "chai": "^4.0.1",
+    "mocha": "^8.3.2",
+    "sinon": "^11.0.0",
+    "source-map-support": "^0.5.21"
+  },
+  "funding": {
+    "type": "opencollective",
+    "url": "https://opencollective.com/typescript-eslint"
+  },
+  "typesVersions": {
+    "<3.8": {
+      "*": [
+        "_ts3.4/*"
+      ]
+    }
+  }
+}

packages/rule-tester/project.json

@@ -0,0 +1,15 @@
+{
+  "name": "rule-tester",
+  "$schema": "../../node_modules/nx/schemas/project-schema.json",
+  "type": "library",
+  "implicitDependencies": [],
+  "targets": {
+    "lint": {
+      "executor": "@nrwl/linter:eslint",
+      "outputs": ["{options.outputFile}"],
+      "options": {
+        "lintFilePatterns": ["packages/rule-tester/**/*.ts"]
+      }
+    }
+  }
+}