From 7d3f2aa8095d6f5882bc91ebee8f5769a7fba35c Mon Sep 17 00:00:00 2001
From: Rich Trott <rtrott@gmail.com>
Date: Thu, 4 Feb 2016 16:27:15 -0800
Subject: [PATCH] test: fix flaky test-dgram-pingpong

There is no guarantee UDP messages will be received. Accommodate the
occasional dropped message.

This is a functionality test, not a performance benchmark. Speed up the
test by sending 5 messages per server rather than 500.

Fixes: https://github.com/nodejs/node/issues/4526
---
 test/sequential/sequential.status      |  1 -
 test/sequential/test-dgram-pingpong.js | 88 ++++++++++----------------
 2 files changed, 33 insertions(+), 56 deletions(-)

diff --git a/test/sequential/sequential.status b/test/sequential/sequential.status
index f872223d370ccd..84760b9c720653 100644
--- a/test/sequential/sequential.status
+++ b/test/sequential/sequential.status
@@ -10,7 +10,6 @@ prefix sequential
 
 [$system==linux]
 test-vm-syntax-error-stderr : PASS,FLAKY
-test-dgram-pingpong         : PASS,FLAKY
 test-http-regr-gh-2928      : PASS,FLAKY
 
 [$system==macos]
diff --git a/test/sequential/test-dgram-pingpong.js b/test/sequential/test-dgram-pingpong.js
index 63d001d0b376a4..6e9e17e87a4d21 100644
--- a/test/sequential/test-dgram-pingpong.js
+++ b/test/sequential/test-dgram-pingpong.js
@@ -1,30 +1,19 @@
 'use strict';
-var common = require('../common');
-var assert = require('assert');
-var Buffer = require('buffer').Buffer;
-var dgram = require('dgram');
-
-var debug = false;
-var tests_run = 0;
+const common = require('../common');
+const assert = require('assert');
+const dgram = require('dgram');
 
 function pingPongTest(port, host) {
-  var callbacks = 0;
-  var N = 500;
-  var count = 0;
+  let pingsReceived = 0;
+  let pongsReceived = 0;
+  let done = false;
 
-  var server = dgram.createSocket('udp4', function(msg, rinfo) {
-    if (debug) console.log('server got: ' + msg +
-                           ' from ' + rinfo.address + ':' + rinfo.port);
+  const N = 5;
 
-    if (/PING/.exec(msg)) {
-      var buf = new Buffer(4);
-      buf.write('PONG');
-      server.send(buf, 0, buf.length,
-                  rinfo.port, rinfo.address,
-                  function(err, sent) {
-                    callbacks++;
-                  });
-    }
+  const server = dgram.createSocket('udp4', function(msg, rinfo) {
+    assert.strictEqual('PING', msg.toString('ascii'));
+    pingsReceived++;
+    server.send('PONG', 0, 4, rinfo.port, rinfo.address);
   });
 
   server.on('error', function(e) {
@@ -32,47 +21,42 @@ function pingPongTest(port, host) {
   });
 
   server.on('listening', function() {
-    console.log('server listening on ' + port + ' ' + host);
+    console.log('server listening on ' + port);
 
-    const buf = new Buffer('PING');
     const client = dgram.createSocket('udp4');
 
-    client.on('message', function(msg, rinfo) {
-      if (debug) console.log('client got: ' + msg +
-                             ' from ' + rinfo.address + ':' + rinfo.port);
-      assert.equal('PONG', msg.toString('ascii'));
-
-      count += 1;
+    client.on('message', function(msg) {
+      assert.strictEqual('PONG', msg.toString('ascii'));
 
-      if (count < N) {
-        client.send(buf, 0, buf.length, port, 'localhost');
-      } else {
-        client.send(buf, 0, buf.length, port, 'localhost', function() {
-          client.close();
-        });
+      pongsReceived++;
+      if (pongsReceived === N) {
+        done = true;
+        client.close();
       }
     });
 
-    client.on('close', function() {
+    client.on('close', common.mustCall(function() {
       console.log('client has closed, closing server');
-      assert.equal(N, count);
-      tests_run += 1;
+      assert(pingsReceived >= N);
+      assert.strictEqual(pongsReceived, N);
       server.close();
-      assert.equal(N - 1, callbacks);
-    });
+    }));
 
     client.on('error', function(e) {
       throw e;
     });
 
-    console.log('Client sending to ' + port + ', localhost ' + buf);
-    client.send(buf, 0, buf.length, port, 'localhost', function(err, bytes) {
-      if (err) {
-        throw err;
-      }
-      console.log('Client sent ' + bytes + ' bytes');
-    });
-    count += 1;
+    console.log('Client sending to ' + port);
+
+    function clientSend() {
+      client.send('PING', 0, 4, port, 'localhost');
+      setImmediate(() => {
+        if (!done)
+          clientSend();
+      });
+    }
+
+    clientSend();
   });
   server.bind(port, host);
 }
@@ -81,9 +65,3 @@ function pingPongTest(port, host) {
 pingPongTest(common.PORT + 0, 'localhost');
 pingPongTest(common.PORT + 1, 'localhost');
 pingPongTest(common.PORT + 2);
-//pingPongTest('/tmp/pingpong.sock');
-
-process.on('exit', function() {
-  assert.equal(3, tests_run);
-  console.log('done');
-});