test: improve test-http-agent-destroyed-socket.js

* wrap callbacks in mustCall()
* Wrap the callbacks which make assertions in common.mustcall()
  to ensure they are called

PR-URL: https://github.com/nodejs/node/pull/11201
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-http-agent-destroyed-socket.js

@@ -1,15 +1,15 @@
 'use strict';
-require('../common');
+const common = require('../common');
 const assert = require('assert');
 const http = require('http');
 
 const server = http.createServer(function(req, res) {
   res.writeHead(200, {'Content-Type': 'text/plain'});
   res.end('Hello World\n');
-}).listen(0, function() {
+}).listen(0, common.mustCall(function() {
   const agent = new http.Agent({maxSockets: 1});
 
-  agent.on('free', function(socket, host, port) {
+  agent.on('free', function(socket) {
     console.log('freeing socket. destroyed? ', socket.destroyed);
   });
 
@@ -20,7 +20,7 @@ const server = http.createServer(function(req, res) {
     path: '/'
   };
 
-  const request1 = http.get(requestOptions, function(response) {
+  const request1 = http.get(requestOptions, common.mustCall(function(response) {
     // assert request2 is queued in the agent
     const key = agent.getName(requestOptions);
     assert.strictEqual(agent.requests[key].length, 1);
@@ -29,7 +29,7 @@ const server = http.createServer(function(req, res) {
       console.log('request1 socket closed');
     });
     response.pipe(process.stdout);
-    response.on('end', function() {
+    response.on('end', common.mustCall(function() {
       console.log('response1 done');
       /////////////////////////////////
       //
@@ -48,17 +48,17 @@ const server = http.createServer(function(req, res) {
         // assert request2 was removed from the queue
         assert(!agent.requests[key]);
         console.log("waiting for request2.onSocket's nextTick");
-        process.nextTick(function() {
+        process.nextTick(common.mustCall(function() {
           // assert that the same socket was not assigned to request2,
           // since it was destroyed.
           assert.notStrictEqual(request1.socket, request2.socket);
           assert(!request2.socket.destroyed, 'the socket is destroyed');
-        });
+        }));
       });
-    });
-  });
+    }));
+  }));
 
-  const request2 = http.get(requestOptions, function(response) {
+  const request2 = http.get(requestOptions, common.mustCall(function(response) {
     assert(!request2.socket.destroyed);
     assert(request1.socket.destroyed);
     // assert not reusing the same socket, since it was destroyed.
@@ -82,5 +82,5 @@ const server = http.createServer(function(req, res) {
       if (gotResponseEnd && gotClose)
         server.close();
     }
-  });
-});
+  }));
+}));