ci: migrate from jest to vitest (#1180)

Author: chimurai

.github/workflows/ci.yml

@@ -153,7 +153,10 @@ jobs:
         run: yarn install --frozen-lockfile --ignore-scripts
 
       - name: yarn test
-        run: yarn test --ci --reporters="default" --reporters="github-actions"
+        run: yarn test
+
+      - name: yarn test:types
+        run: yarn test:types
 
         env:
           CI: true

README.md

@@ -623,7 +623,7 @@ $ yarn build
 $ yarn test
 
 # code coverage
-$ yarn cover
+$ yarn coverage
 
 # check spelling mistakes
 $ yarn spellcheck

jest.config.js

@@ -18,8 +18,9 @@
     "prettier": "prettier --list-different \"**/*.{js,ts,md,yml,json,html}\"",
     "prettier:fix": "prettier --write \"**/*.{js,ts,md,yml,json,html}\"",
     "build": "tsc --build",
-    "test": "jest",
-    "coverage": "jest --coverage",
+    "test": "vitest run",
+    "test:types": "tsc --project tsconfig.test.json --noEmit",
+    "coverage": "vitest run --coverage",
     "prepare": "husky && patch-package",
     "prepack": "yarn clean && yarn test && yarn build",
     "spellcheck": "npx --yes cspell --show-context --show-suggestions '**/*.*'"
@@ -64,28 +65,27 @@
     "@types/eslint": "9.6.1",
     "@types/express": "5.0.6",
     "@types/is-glob": "4.0.4",
-    "@types/jest": "30.0.0",
     "@types/micromatch": "4.0.10",
     "@types/node": "24.10.2",
     "@types/supertest": "7.2.0",
     "@types/ws": "8.18.1",
+    "@vitest/coverage-v8": "^4.1.2",
     "body-parser": "2.2.2",
     "eslint": "10.0.2",
     "express": "5.2.1",
     "get-port": "5.1.1",
     "globals": "17.3.0",
     "husky": "9.1.7",
-    "jest": "30.2.0",
     "lint-staged": "16.3.0",
     "mockttp": "4.2.1",
     "open": "8.4.2",
     "patch-package": "8.0.1",
     "pkg-pr-new": "0.0.65",
     "prettier": "3.8.1",
     "supertest": "7.2.2",
-    "ts-jest": "29.4.6",
     "typescript": "5.9.3",
     "typescript-eslint": "8.56.1",
+    "vitest": "^4.1.2",
     "ws": "8.19.0"
   },
   "dependencies": {

jest.setup.js

@@ -1,7 +1,11 @@
+import type * as http from 'node:http';
+
 import { ERRORS } from './errors';
 import { Options } from './types';
 
-export function verifyConfig<TReq, TRes>(options: Options<TReq, TRes>): void {
+export function verifyConfig<TReq extends http.IncomingMessage, TRes extends http.ServerResponse>(
+  options: Options<TReq, TRes>,
+): void {
   if (!options.target && !options.router) {
     throw new Error(ERRORS.ERR_CONFIG_FACTORY_TARGET_MISSING);
   }

package.json

@@ -1,4 +1,4 @@
-import * as createDebug from 'debug';
+import createDebug from 'debug';
 
 /**
  * Debug instance with the given namespace: http-proxy-middleware

src/configuration.ts

@@ -4,8 +4,8 @@ import { HttpProxyMiddleware } from './http-proxy-middleware';
 import type { NextFunction, Options, RequestHandler } from './types';
 
 export function createProxyMiddleware<
-  TReq = http.IncomingMessage,
-  TRes = http.ServerResponse,
+  TReq extends http.IncomingMessage = http.IncomingMessage,
+  TRes extends http.ServerResponse = http.ServerResponse,
   TNext = NextFunction,
 >(options: Options<TReq, TRes>): RequestHandler<TReq, TRes, TNext> {
   const { middleware } = new HttpProxyMiddleware<TReq, TRes>(options);

src/debug.ts

@@ -1,3 +1,5 @@
+import type * as http from 'node:http';
+
 import {
   debugProxyErrorsPlugin,
   errorResponsePlugin,
@@ -6,7 +8,9 @@ import {
 } from './plugins/default';
 import type { Options, Plugin } from './types';
 
-export function getPlugins<TReq, TRes>(options: Options<TReq, TRes>): Plugin<TReq, TRes>[] {
+export function getPlugins<TReq extends http.IncomingMessage, TRes extends http.ServerResponse>(
+  options: Options<TReq, TRes>,
+): Plugin<TReq, TRes>[] {
   // don't load default errorResponsePlugin if user has specified their own
   const maybeErrorResponsePlugin = options.on?.error ? [] : [errorResponsePlugin];
 

src/factory.ts

@@ -14,7 +14,10 @@ import * as Router from './router';
 import type { Filter, Logger, Options, RequestHandler } from './types';
 import { getFunctionName } from './utils/function';
 
-export class HttpProxyMiddleware<TReq, TRes> {
+export class HttpProxyMiddleware<
+  TReq extends http.IncomingMessage = http.IncomingMessage,
+  TRes extends http.ServerResponse = http.ServerResponse,
+> {
   private wsInternalSubscribed = false;
   private serverOnCloseSubscribed = false;
   private proxyOptions: Options<TReq, TRes>;
@@ -44,7 +47,11 @@ export class HttpProxyMiddleware<TReq, TRes> {
   }
 
   // https://github.com/Microsoft/TypeScript/wiki/'this'-in-TypeScript#red-flags-for-this
-  public middleware: RequestHandler = (async (req, res, next?) => {
+  public middleware: RequestHandler<TReq, TRes> = (async (
+    req: TReq,
+    res: TRes,
+    next?: (err?: unknown) => void,
+  ) => {
     if (this.shouldProxy(this.proxyOptions.pathFilter, req)) {
       let activeProxyOptions: Options<TReq, TRes>;
       try {