fix: add use to types (#9)

README.md

@@ -4,7 +4,7 @@
 
 This plugin adds full [Express](http://expressjs.com) compatibility to Fastify, it exposes the same `use` function of Express, and it allows you to use any Express middleware or application.<br/>
 
-| **Note**   |  This plugin should not be used as a long-term solution, it aims to help you have a smooth transition from Express to Fastify, but you should migrate your Express specific code to Fastify during time.  |
+| **Note**   |  This plugin should not be used as a long-term solution, it aims to help you have a smooth transition from Express to Fastify, but you should migrate your Express specific code to Fastify over time.  |
 | ----   |  :----  |
 
 ## Install
@@ -144,6 +144,10 @@ async function subsystem (fastify, opts) {
 }
 ```
 
+## TypeScript support
+
+To use this module with TypeScript, make sure to install `@types/express`.
+
 ## Middlewares alternatives
 
 Fastify offers some alternatives to the most commonly used middlewares, following, you can find a list.

index.d.ts

@@ -1,8 +1,13 @@
 import { Application } from 'express'
 import { FastifyPluginCallback } from 'fastify'
 
-declare module "fastify" {
+declare module 'fastify' {
   interface FastifyInstance {
+    /**
+     * Express middleware function
+     */
+    use: Application['use']
+
     /**
      * Express application instance
      */

test/types/index.ts

@@ -6,3 +6,7 @@ const app = Fastify()
 app.register(fastifyExpress)
 
 app.express.disable('x-powered-by')
+
+app.use('/world', (_req, res) => {
+  res.sendStatus(200)
+})