test: refactor test-http-after-connect.js

- Replace assert.equal() to assert.strictEqual()
- Replace var with const where applicable
- Removed firstBodyChunk which is never used
- Remove the process.on('exit', ...) and replace its functionality by
- Using common.mustCall() where applicable

PR-URL: nodejs#10229
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Italo A. Casas <me@italoacasas.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

test/parallel/test-http-after-connect.js

@@ -1,72 +1,62 @@
 'use strict';
-require('../common');
-var assert = require('assert');
-var http = require('http');
+const common = require('../common');
+const assert = require('assert');
+const http = require('http');
 
-var serverConnected = false;
-var serverRequests = 0;
 var clientResponses = 0;
 
-var server = http.createServer(function(req, res) {
+const server = http.createServer(common.mustCall(function(req, res) {
   console.error('Server got GET request');
   req.resume();
-  ++serverRequests;
   res.writeHead(200);
   res.write('');
   setTimeout(function() {
     res.end(req.url);
   }, 50);
-});
-server.on('connect', function(req, socket, firstBodyChunk) {
+}, 2));
+server.on('connect', common.mustCall(function(req, socket) {
   console.error('Server got CONNECT request');
-  serverConnected = true;
   socket.write('HTTP/1.1 200 Connection established\r\n\r\n');
   socket.resume();
   socket.on('end', function() {
     socket.end();
   });
-});
+}));
 server.listen(0, function() {
-  var req = http.request({
+  const req = http.request({
     port: this.address().port,
     method: 'CONNECT',
     path: 'google.com:80'
   });
-  req.on('connect', function(res, socket, firstBodyChunk) {
+  req.on('connect', common.mustCall(function(res, socket) {
     console.error('Client got CONNECT response');
     socket.end();
     socket.on('end', function() {
       doRequest(0);
       doRequest(1);
     });
     socket.resume();
-  });
+  }));
   req.end();
 });
 
 function doRequest(i) {
   http.get({
     port: server.address().port,
     path: '/request' + i
-  }, function(res) {
+  }, common.mustCall(function(res) {
     console.error('Client got GET response');
     var data = '';
     res.setEncoding('utf8');
     res.on('data', function(chunk) {
       data += chunk;
     });
     res.on('end', function() {
-      assert.equal(data, '/request' + i);
+      assert.strictEqual(data, '/request' + i);
       ++clientResponses;
       if (clientResponses === 2) {
         server.close();
       }
     });
-  });
+  }));
 }
-
-process.on('exit', function() {
-  assert(serverConnected);
-  assert.equal(serverRequests, 2);
-  assert.equal(clientResponses, 2);
-});