fixup! Simplify reply sent monitoring (fastify#3072)

lib/handleRequest.js

@@ -75,9 +75,7 @@ function handler (request, reply) {
 }
 
 function preValidationCallback (err, request, reply) {
-  if (reply.sent === true ||
-    reply.raw.writableEnded === true ||
-    reply.raw.writable === false) return
+  if (reply.sent === true) return
 
   if (err != null) {
     reply.send(err)
@@ -109,9 +107,7 @@ function preValidationCallback (err, request, reply) {
 }
 
 function preHandlerCallback (err, request, reply) {
-  if (reply.sent ||
-    reply.raw.writableEnded === true ||
-    reply.raw.writable === false) return
+  if (reply.sent) return
 
   if (err != null) {
     reply.send(err)

lib/reply.js

@@ -81,9 +81,10 @@ Object.defineProperties(Reply.prototype, {
       // response has ended. The response.writableEnded property was added in
       // Node.js v12.9.0. Since fastify supports older Node.js versions as well,
       // we have to take response.finished property in consideration when
-      // applicable.
+      // applicable. The response.finished will always be true when the request
+      // method is HEAD, so we have to combine that with response.headersSent.
       // TODO: remove fallback when the lowest supported Node.js version >= v12.9.0
-      return (this[kReplySentOverwritten] || (typeof this.raw.writableEnded !== 'undefined' ? this.raw.writableEnded : this.raw.finished)) === true
+      return (this[kReplySentOverwritten] || (typeof this.raw.writableEnded !== 'undefined' ? this.raw.writableEnded : (this.raw.headersSent && this.raw.finished))) === true
     },
     set (value) {
       if (value !== true) {

test/internals/handleRequest.test.js

@@ -1,7 +1,6 @@
 'use strict'
 
 const { test } = require('tap')
-const semver = require('semver')
 const handleRequest = require('../../lib/handleRequest')
 const internals = require('../../lib/handleRequest')[Symbol.for('internals')]
 const Request = require('../../lib/request')
@@ -108,12 +107,8 @@ test('handler function - preValidationCallback with finished response', t => {
   t.plan(0)
   const res = {}
   // Be sure to check only `writableEnded` where is available
-  if (semver.gte(process.versions.node, '12.9.0')) {
-    res.writableEnded = true
-  } else {
-    res.writable = false
-    res.finished = true
-  }
+  res.writableEnded = true
+
   res.end = () => {
     t.fail()
   }
@@ -138,7 +133,7 @@ test('handler function - preValidationCallback with finished response (< v12.9.0
   t.plan(0)
   const res = {}
   // Be sure to check only `writableEnded` where is available
-  res.writable = false
+  res.headersSent = true
   res.finished = true
 
   res.end = () => {

test/internals/reply.test.js

@@ -1694,10 +1694,10 @@ test('reply.sent should read from response.writableEnded if it is defined', t =>
   t.equal(reply.sent, true)
 })
 
-test('reply.sent should read from response.finished if response.writableEnded is not defined', t => {
+test('reply.sent should read from response.headersSent and response.finished if response.writableEnded is not defined', t => {
   t.plan(1)
 
-  const reply = new Reply({ finished: true }, {}, {})
+  const reply = new Reply({ headersSent: true, finished: true }, {}, {})
 
   t.equal(reply.sent, true)
 })