remove app.use and fix middleware tests

docs/Migration-Guide-V3.md

@@ -32,6 +32,10 @@ await fastify.register(require('fastify-express'));
 fastify.use(require('cors')());
 ```
 
+**v4:**
+
+Starting v4 we have deprecated the use of `.use`. Both `middie` and `fastify-express` will still be there and maintained.
+
 ### Changed logging serialization ([#2017](https://github.com/fastify/fastify/pull/2017))
 
 The logging [Serializers](Logging.md) have been updated to now Fastify

fastify.js

@@ -48,7 +48,6 @@ const { defaultInitOptions } = getSecuredInitialConfig
 
 const {
   FST_ERR_BAD_URL,
-  FST_ERR_MISSING_MIDDLEWARE,
   AVVIO_ERRORS_MAP,
   appendStackTrace
 } = require('./lib/errors')
@@ -324,11 +323,6 @@ function fastify (options) {
     }
   })
 
-  // We are adding `use` to the fastify prototype so the user
-  // can still access it (and get the expected error), but `decorate`
-  // will not detect it, and allow the user to override it.
-  Object.setPrototypeOf(fastify, { use })
-
   if (options.schemaErrorFormatter) {
     validateSchemaErrorFormatter(options.schemaErrorFormatter)
     fastify[kSchemaErrorFormatter] = options.schemaErrorFormatter.bind(fastify)
@@ -493,10 +487,6 @@ function fastify (options) {
     }
   }
 
-  function use () {
-    throw new FST_ERR_MISSING_MIDDLEWARE()
-  }
-
   // Used exclusively in TypeScript contexts to enable auto type inference from JSON schema.
   function withTypeProvider () {
     return this

lib/errors.js

@@ -105,15 +105,6 @@ const codes = {
     "A callback for '%s' hook timed out. You may have forgotten to call 'done' function or to resolve a Promise"
   ),
 
-  /**
-   * Middlewares
-   */
-  FST_ERR_MISSING_MIDDLEWARE: createError(
-    'FST_ERR_MISSING_MIDDLEWARE',
-    'You must register a plugin for handling middlewares, visit fastify.io/docs/latest/Middleware/ for more info.',
-    500
-  ),
-
   /**
    * logger
   */

test/middleware.test.js

@@ -3,22 +3,9 @@
 const { test } = require('tap')
 const Fastify = require('..')
 const {
-  FST_ERR_DEC_ALREADY_PRESENT,
-  FST_ERR_MISSING_MIDDLEWARE
+  FST_ERR_DEC_ALREADY_PRESENT
 } = require('../lib/errors')
 
-test('Should throw if the basic use API has not been overridden', t => {
-  t.plan(1)
-  const fastify = Fastify()
-
-  try {
-    fastify.use()
-    t.fail('Should throw')
-  } catch (err) {
-    t.ok(err instanceof FST_ERR_MISSING_MIDDLEWARE)
-  }
-})
-
 test('Should be able to override the default use API', t => {
   t.plan(1)
   const fastify = Fastify()
@@ -38,7 +25,7 @@ test('Cannot decorate use twice', t => {
 })
 
 test('Encapsulation works', t => {
-  t.plan(2)
+  t.plan(1)
   const fastify = Fastify()
 
   fastify.register((instance, opts, done) => {
@@ -47,15 +34,5 @@ test('Encapsulation works', t => {
     done()
   })
 
-  fastify.register((instance, opts, done) => {
-    try {
-      instance.use()
-      t.fail('Should throw')
-    } catch (err) {
-      t.ok(err instanceof FST_ERR_MISSING_MIDDLEWARE)
-    }
-    done()
-  })
-
   fastify.ready()
 })