test: cleanup test-tls-connect-given-socket.js

Changed vars to consts and lets, assert.equals to
assert.strictEquals and added common.mustCall around callbacks.
Switched to arrow functions.

PR-URL: #8616
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ilkka Myller <ilkka.myller@nodefield.com>

test/parallel/test-tls-connect-given-socket.js

@@ -1,78 +1,78 @@
 'use strict';
-var common = require('../common');
-var assert = require('assert');
+const common = require('../common');
+const assert = require('assert');
 
 if (!common.hasCrypto) {
   common.skip('missing crypto');
   return;
 }
-var tls = require('tls');
+const tls = require('tls');
 
-var net = require('net');
-var fs = require('fs');
-var path = require('path');
+const net = require('net');
+const fs = require('fs');
+const path = require('path');
 
-var serverConnected = 0;
-var clientConnected = 0;
+let serverConnected = 0;
+let clientConnected = 0;
 
-var options = {
+const options = {
   key: fs.readFileSync(path.join(common.fixturesDir, 'test_key.pem')),
   cert: fs.readFileSync(path.join(common.fixturesDir, 'test_cert.pem'))
 };
 
-var server = tls.createServer(options, function(socket) {
+const server = tls.createServer(options, (socket) => {
   serverConnected++;
   socket.end('Hello');
-}).listen(0, function() {
-  var waiting = 2;
+}).listen(0, () => {
+  let waiting = 2;
   function establish(socket) {
-    var client = tls.connect({
+    const client = tls.connect({
       rejectUnauthorized: false,
       socket: socket
-    }, function() {
+    }, () => {
       clientConnected++;
-      var data = '';
-      client.on('data', function(chunk) {
+      let data = '';
+      client.on('data', common.mustCall((chunk) => {
         data += chunk.toString();
-      });
-      client.on('end', function() {
-        assert.equal(data, 'Hello');
+      }));
+      client.on('end', common.mustCall(() => {
+        assert.strictEqual(data, 'Hello');
         if (--waiting === 0)
           server.close();
-      });
+      }));
     });
     assert(client.readable);
     assert(client.writable);
 
     return client;
   }
 
+  const { port } = server.address();
+
   // Immediate death socket
-  var immediateDeath = net.connect(this.address().port);
+  const immediateDeath = net.connect(port);
   establish(immediateDeath).destroy();
 
   // Outliving
-  var outlivingTCP = net.connect(this.address().port);
-  outlivingTCP.on('connect', function() {
+  const outlivingTCP = net.connect(port, common.mustCall(() => {
     outlivingTLS.destroy();
     next();
-  });
-  var outlivingTLS = establish(outlivingTCP);
+  }));
+  const outlivingTLS = establish(outlivingTCP);
 
   function next() {
     // Already connected socket
-    var connected = net.connect(server.address().port, function() {
+    const connected = net.connect(port, common.mustCall(() => {
       establish(connected);
-    });
+    }));
 
     // Connecting socket
-    var connecting = net.connect(server.address().port);
+    const connecting = net.connect(port);
     establish(connecting);
-
   }
 });
 
-process.on('exit', function() {
-  assert.equal(serverConnected, 2);
-  assert.equal(clientConnected, 2);
+process.on('exit', () => {
+  assert.strictEqual(serverConnected, 2);
+  assert.strictEqual(clientConnected, 2);
 });