refactor: setup eslint and autofix

.eslintignore

@@ -0,0 +1,6 @@
+.yalc
+.vscode
+.github
+node_modules
+dist-cjs
+dist-esm

.eslintrc

@@ -0,0 +1,57 @@
+{
+  "root": true,
+  "parser": "@typescript-eslint/parser",
+  "parserOptions": {
+    "project": ["tsconfig.json"]
+  },
+  "plugins": [
+    // This enables using new lint rules powered by the TypeScript compiler API.
+    // https://github.com/typescript-eslint/typescript-eslint
+    "@typescript-eslint",
+    // This makes it so the IDE reports lint rejections as warnings only. This is
+    // better than errors because most lint rejections are not runtime errors. This
+    // allows IDE errors to be exclusive for e.g. static type errors which often are
+    // reflective of real runtime errors.
+    // https://github.com/bfanger/eslint-plugin-only-warn
+    "only-warn",
+    // This enables the use of a lint rule to reject function declarations. This is
+    // preferable as a way to encourage higher order function usage. For example it is not
+    // possible to wrap a function declaration with Open Telemetry instrumentation but it is
+    // possible to wrap an arrow function since its an expression.
+    // https://github.com/TristonJ/eslint-plugin-prefer-arrow
+    "prefer-arrow",
+    // This enables the use of a lint rule to reject use of @deprecated functions.
+    // https://github.com/gund/eslint-plugin-deprecation
+    "deprecation",
+    // Import sorting integrated into ESLint.
+    // https://github.com/lydell/eslint-plugin-simple-import-sort
+    "simple-import-sort",
+    // https://github.com/microsoft/tsdoc/tree/master/eslint-plugin
+    "tsdoc"
+  ],
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/eslint-recommended",
+    "plugin:@typescript-eslint/recommended",
+    "plugin:@typescript-eslint/recommended-requiring-type-checking",
+    "prettier"
+  ],
+  "overrides": [],
+  "rules": {
+    "quotes": ["warn", "backtick"],
+    "tsdoc/syntax": "warn",
+    "simple-import-sort/imports": [
+      "warn",
+      {
+        "groups": []
+      }
+    ],
+    "simple-import-sort/exports": "warn",
+    "deprecation/deprecation": "warn",
+    "prefer-arrow/prefer-arrow-functions": "warn",
+    // TypeScript makes these safe & effective
+    "no-case-declarations": "off",
+    // Same approach used by TypeScript noUnusedLocals
+    "@typescript-eslint/no-unused-vars": ["warn", { "varsIgnorePattern": "^_", "argsIgnorePattern": "^_" }]
+  }
+}

jest.config.ts

@@ -20,7 +20,7 @@ const config = {
     `jest-watch-select-projects`,
     `jest-watch-suspend`,
   ],
-  setupFiles: ['./tests/_setup.ts'],
+  setupFiles: [`./tests/_setup.ts`],
 }
 
 export default config

jest.config.unit.ts

@@ -2,10 +2,10 @@ import baseConfig from './jest.config'
 
 const config = {
   ...baseConfig,
-  testRegex: 'src/.*\\.spec\\.ts$',
+  testRegex: `src/.*\\.spec\\.ts$`,
   displayName: {
-    name: 'Unit',
-    color: 'blue',
+    name: `Unit`,
+    color: `blue`,
   },
 }
 

package.json

@@ -22,6 +22,8 @@
     "build": "yarn clean && yarn build:cjs && yarn build:esm",
     "build:cjs": "tsc --project tsconfig.cjs.json",
     "build:esm": "tsc --project tsconfig.esm.json",
+    "lint": "eslint . --ext .ts,.tsx --fix",
+    "lint:check": "eslint . --ext .ts,.tsx --max-warnings 0",
     "clean": "rm -rf dist-cjs dist-esm node_modules/.cache",
     "dev": "tsc --watch",
     "type-check": "yarn tsc --noEmit",
@@ -59,10 +61,20 @@
     "@swc/jest": "^0.2.20",
     "@tsconfig/node14": "^1.0.1",
     "@types/common-tags": "1.8.1",
+    "@types/eslint": "^8",
     "@types/jest": "27.4.1",
     "@types/node": "17.0.21",
     "@types/tmp": "0.2.3",
+    "@typescript-eslint/eslint-plugin": "^5.13.0",
+    "@typescript-eslint/parser": "^5.13.0",
     "doctoc": "1.4.0",
+    "eslint": "^8.10.0",
+    "eslint-config-prettier": "^8.5.0",
+    "eslint-plugin-deprecation": "^1.3.2",
+    "eslint-plugin-only-warn": "^1.0.3",
+    "eslint-plugin-prefer-arrow": "^1.2.3",
+    "eslint-plugin-simple-import-sort": "^7.0.0",
+    "eslint-plugin-tsdoc": "^0.2.14",
     "jest": "27.5.1",
     "jest-watch-select-projects": "^2.0.0",
     "jest-watch-suspend": "1.1.2",