test: fix flaky test-dgram-empty-packet & friends

* Liberal use of common.mustCall() * Rename test-dgram-empty-packet -> test-dgram-send-empty-packet * Remove use of timers to avoid CI failures like seen in the Ref below: ``` not ok 237 parallel/test-dgram-empty-packet --- duration_ms: 0.717 severity: fail stack: |- ... throw new Error('Timeout'); ^ Error: Timeout at Timeout._onTimeout ... at ontimeout (timers.js:365:14) at tryOnTimeout (timers.js:237:5) at Timer.listOnTimeout (timers.js:207:5) ``` Refs: https://ci.nodejs.org/job/node-test-commit-freebsd/5341/nodes=freebsd11-x64/console:
nodejs · Trott · Nov 21, 2016 · Nov 23, 2016 · Nov 24, 2016 · Nov 24, 2016
commit 5b2178a2f5db5e41bd66602ffeace5bb65c97888
diff --git a/test/parallel/test-dgram-empty-packet.js b/test/parallel/test-dgram-empty-packet.js
diff --git a/test/parallel/test-dgram-send-empty-array.js b/test/parallel/test-dgram-send-empty-array.js
@@ -1,14 +1,15 @@
 'use strict';
 
 const common = require('../common');
-const assert = require('assert');
-const dgram = require('dgram');
 
 if (common.isOSX) {
   common.skip('because of 17894467 Apple bug');
   return;
 }
 
+const assert = require('assert');
+const dgram = require('dgram');
+
 const client = dgram.createSocket('udp4');
 
 client.on('message', common.mustCall(function onMessage(buf, info) {
@@ -17,8 +18,8 @@ client.on('message', common.mustCall(function onMessage(buf, info) {
   client.close();
 }));
 
-client.on('listening', function() {
+client.on('listening', common.mustCall(function() {
   client.send([], this.address().port, common.localhostIPv4);
-});
+}));
 
 client.bind(0);
diff --git a/test/parallel/test-dgram-send-empty-buffer.js b/test/parallel/test-dgram-send-empty-buffer.js
@@ -1,26 +1,22 @@
 'use strict';
 const common = require('../common');
-const dgram = require('dgram');
 
 if (common.isOSX) {
   common.skip('because of 17894467 Apple bug');
   return;
 }
 
+const dgram = require('dgram');
+
 const client = dgram.createSocket('udp4');
 
-client.bind(0, function() {
+client.bind(0, common.mustCall(function() {
   const port = this.address().port;
 
   client.on('message', common.mustCall(function onMessage(buffer, bytes) {
-    clearTimeout(timer);
     client.close();
   }));
 
   const buf = Buffer.alloc(0);
-  client.send(buf, 0, 0, port, '127.0.0.1', function(err, len) { });
-
-  const timer = setTimeout(function() {
-    throw new Error('Timeout');
-  }, common.platformTimeout(200));
-});
+  client.send(buf, 0, 0, port, '127.0.0.1', common.mustCall(function() { }));
+}));
diff --git a/test/parallel/test-dgram-send-empty-packet.js b/test/parallel/test-dgram-send-empty-packet.js
@@ -0,0 +1,27 @@
+'use strict';
+const common = require('../common');
+
+if (common.isOSX) {
+  common.skip('because of 17894467 Apple bug');
+  return;
+}
+
+const dgram = require('dgram');
+
+const client = dgram.createSocket('udp4');
+
+client.bind(0, common.mustCall(function() {
+
+  function callback(firstArg) {
+    // First time through, firstArg should be null.
+    // Second time, it should be the buffer.
+    if (firstArg instanceof Buffer)
+      client.close();
+  }
+
+  client.on('message', common.mustCall(callback));
+
+  const port = this.address().port;
+  const buf = Buffer.alloc(1);
+  client.send(buf, 0, 0, port, '127.0.0.1', common.mustCall(callback));
+}));