ci(eslint): migrate to eslint + prettier

.eslintrc.js

@@ -0,0 +1,18 @@
+module.exports = {
+  parser: '@typescript-eslint/parser',
+  parserOptions: {
+    ecmaVersion: 2020,
+    sourceType: 'module',
+  },
+  extends: [
+    'plugin:@typescript-eslint/recommended',
+    'prettier/@typescript-eslint',
+    'plugin:prettier/recommended',
+  ],
+  rules: {
+    '@typescript-eslint/no-unused-vars': [
+      'error',
+      { vars: 'all', args: 'none', ignoreRestSiblings: false },
+    ],
+  },
+};

.github/workflows/lint.yml

@@ -3,20 +3,27 @@ name: Lint
 on: ["push","pull_request"]
 
 jobs:
-  build:
-    name: Lint
-
+  run-linters:
+    name: Run linters
     runs-on: ubuntu-latest
 
-    strategy:
-      matrix:
-        node-version: [14.x]
-
     steps:
-    - uses: actions/checkout@v2
-    - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v1
-      with:
-        node-version: ${{ matrix.node-version }}
-    - run: yarn install
-    - run: yarn lint
+      - name: Check out Git repository
+        uses: actions/checkout@v2
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v1
+        with:
+          node-version: 14
+
+      # ESLint and Prettier must be in `package.json`
+      - name: Install Node.js dependencies
+        run: yarn install
+
+      - name: Run linters
+        uses: wearerequired/lint-action@v1
+        with:
+          github_token: ${{ secrets.github_token }}
+          # Enable linters
+          eslint: true
+          prettier: true

.lintstagedrc

@@ -1,3 +1,4 @@
 {
   "**/*.{js,ts,md}": "prettier --write",
+  "**/*.{js,ts}": "eslint --fix",
 }

package.json

@@ -9,10 +9,12 @@
   ],
   "scripts": {
     "clean": "rm -rf dist && rm -rf coverage",
-    "lint": "yarn lint:prettier && yarn lint:tslint",
-    "lint:prettier": "prettier --check \"**/*.{js,ts,md}\"",
-    "lint:tslint": "yarn tslint -c tslint.json '{lib,test}/**/*.ts'",
-    "lint:fix": "prettier --write \"**/*.{js,ts,md}\"",
+    "lint": "yarn prettier && yarn eslint",
+    "lint:fix": "yarn prettier:fix && yarn eslint:fix",
+    "lint:eslint": "eslint '{lib,test}/**/*.ts'",
+    "lint:eslint:fix": "yarn eslint --fix",
+    "lint:prettier": "prettier --list-different \"**/*.{js,ts,md}\"",
+    "lint:prettier:fix": "prettier --write \"**/*.{js,ts,md}\"",
     "build": "tsc",
     "pretest": "yarn build",
     "test": "jest",
@@ -55,8 +57,14 @@
     "@types/micromatch": "^4.0.1",
     "@types/node": "^14.6.2",
     "@types/supertest": "^2.0.10",
+    "@types/ws": "^7.2.6",
+    "@typescript-eslint/eslint-plugin": "^3.10.1",
+    "@typescript-eslint/parser": "^3.10.1",
     "browser-sync": "^2.26.12",
     "connect": "^3.7.0",
+    "eslint": "^7.7.0",
+    "eslint-config-prettier": "^6.11.0",
+    "eslint-plugin-prettier": "^3.1.4",
     "express": "^4.17.1",
     "husky": "^4.2.5",
     "jest": "^26.4.2",
@@ -66,8 +74,6 @@
     "prettier": "^2.1.1",
     "supertest": "^4.0.2",
     "ts-jest": "^26.3.0",
-    "tslint": "^6.1.3",
-    "tslint-config-prettier": "^1.18.0",
     "typescript": "^4.0.2",
     "ws": "^7.3.1"
   },

test/e2e/_utils.ts

@@ -1,14 +1,15 @@
 import * as express from 'express';
+import { Express, RequestHandler } from 'express';
 
 export { createProxyMiddleware } from '../../dist/index';
 
-export function createApp(middleware) {
+export function createApp(middleware: RequestHandler): Express {
   const app = express();
   app.use(middleware);
   return app;
 }
 
-export function createAppWithPath(path, middleware) {
+export function createAppWithPath(path: string | string[], middleware: RequestHandler): Express {
   const app = express();
   app.use(path, middleware);
   return app;

test/e2e/express-router.spec.ts

@@ -12,16 +12,14 @@ describe('Usage in Express', () => {
   });
 
   afterEach(() => {
-    // tslint:disable-next-line: no-unused-expression
-    server && server.close();
+    server?.close();
   });
 
   // https://github.com/chimurai/http-proxy-middleware/issues/94
   describe('Express Sub Route', () => {
     beforeEach(() => {
       // sub route config
-      // @ts-ignore: Only a void function can be called with the 'new' keyword.ts(2350)
-      const sub = new express.Router();
+      const sub = express.Router();
 
       function filter(pathname, req) {
         const urlFilter = new RegExp('^/sub/api');

test/e2e/http-proxy-middleware.spec.ts

@@ -19,19 +19,19 @@ describe('E2E http-proxy-middleware', () => {
       beforeEach(() => {
         isSkipped = false;
 
-        let middleware;
-
         const mockReq = { url: '/foo/bar', originalUrl: '/foo/bar' };
         const mockRes = {};
         const mockNext = () => {
           // mockNext will be called when request is not proxied
           isSkipped = true;
         };
 
-        middleware = createProxyMiddleware('/api', {
+        const middleware = createProxyMiddleware('/api', {
           target: `http://localhost:8000`,
         });
-        middleware(mockReq, mockRes, mockNext);
+
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        middleware(mockReq as any, mockRes as any, mockNext);
       });
 
       it('should not proxy requests when request url does not match context', () => {

test/e2e/websocket.spec.ts

@@ -21,7 +21,6 @@ describe('E2E WebSocket proxy', () => {
 
     proxyServer = express().use(proxy).listen(3000);
 
-    // @ts-ignore: Expected arguments error
     wss = new WebSocketServer({ port: 9000 });
 
     wss.on('connection', function connection(websocket) {
@@ -47,7 +46,6 @@ describe('E2E WebSocket proxy', () => {
         // do a second http request to make
         // sure only 1 listener subscribes to upgrade request
         http.get('http://localhost:3000/', () => {
-          // @ts-ignore: Expected arguments error
           ws = new WebSocket('ws://localhost:3000/socket');
 
           ws.on('message', function incoming(message) {
@@ -71,7 +69,6 @@ describe('E2E WebSocket proxy', () => {
     beforeEach((done) => {
       proxyServer.on('upgrade', proxy.upgrade);
 
-      // @ts-ignore: Expected arguments error
       ws = new WebSocket('ws://localhost:3000/socket');
 
       ws.on('message', function incoming(message) {
@@ -104,7 +101,6 @@ describe('E2E WebSocket proxy', () => {
     beforeEach((done) => {
       proxyServer.on('upgrade', proxy.upgrade);
 
-      // @ts-ignore: Expected arguments error
       ws = new WebSocket('ws://localhost:3000/socket');
 
       ws.on('message', function incoming(message) {
@@ -138,7 +134,6 @@ describe('E2E WebSocket proxy', () => {
     beforeEach((done) => {
       proxyServer.on('upgrade', proxy.upgrade);
 
-      // @ts-ignore: Expected arguments error
       ws = new WebSocket('ws://localhost:3000/socket');
 
       ws.on('message', function incoming(message) {

test/types.spec.ts

@@ -118,39 +118,39 @@ describe('http-proxy-middleware TypeScript Types', () => {
 
     describe('HPM http-proxy events', () => {
       it('should have onError type', () => {
-        // tslint:disable no-empty
+        // eslint-disable-next-line @typescript-eslint/no-empty-function
         options = { onError: (err, req, res) => {} };
         expect(options).toBeDefined();
       });
 
       it('should have onProxyReq type', () => {
-        // tslint:disable no-empty
+        // eslint-disable-next-line @typescript-eslint/no-empty-function
         options = { onProxyReq: (proxyReq, req, res) => {} };
         expect(options).toBeDefined();
       });
 
       it('should have onProxyRes type', () => {
-        // tslint:disable no-empty
+        // eslint-disable-next-line @typescript-eslint/no-empty-function
         options = { onProxyRes: (proxyRes, req, res) => {} };
         expect(options).toBeDefined();
       });
 
       it('should have onProxyReqWs type', () => {
         options = {
-          // tslint:disable no-empty
+          // eslint-disable-next-line @typescript-eslint/no-empty-function
           onProxyReqWs: (proxyReq, req, socket, opts, head) => {},
         };
         expect(options).toBeDefined();
       });
 
       it('should have onOpen type', () => {
-        // tslint:disable no-empty
+        // eslint-disable-next-line @typescript-eslint/no-empty-function
         options = { onOpen: (proxySocket) => {} };
         expect(options).toBeDefined();
       });
 
       it('should have onClose type', () => {
-        // tslint:disable no-empty
+        // eslint-disable-next-line @typescript-eslint/no-empty-function
         options = { onClose: (res, socket, head) => {} };
         expect(options).toBeDefined();
       });

test/unit/context-matcher.spec.ts

@@ -257,7 +257,7 @@ describe('Context Matching', () => {
       });
 
       it('should not throw error with Function', () => {
-        // tslint:disable-next-line: no-empty
+        // eslint-disable-next-line @typescript-eslint/no-empty-function
         expect(testContext(() => {})).not.toThrowError(Error);
       });
     });

test/unit/path-rewriter.spec.ts

@@ -171,12 +171,12 @@ describe('Path rewriting', () => {
     });
 
     it('should not throw when function config is provided', () => {
-      // tslint:disable-next-line: no-empty
+      // eslint-disable-next-line @typescript-eslint/no-empty-function
       expect(badFn(() => {})).not.toThrowError(Error);
     });
 
     it('should not throw when async function config is provided', () => {
-      // tslint:disable-next-line: no-empty
+      // eslint-disable-next-line @typescript-eslint/no-empty-function
       expect(badFn(async () => {})).not.toThrowError(Error);
     });
   });