test: fix flaky test-http-client-timeout-with-data

test-http-client-timeout-with-data has failed here and there in CI on
FreeBSD and OS X. The test has a socket timeout set to 50ms and a timer
set for 100ms. However, they are not necessarily set in the same tick of
the event loop and their ordering is therefore not guaranteed.
Instead of using a timer, this change listens for an event on the
listener to know when the socket timeout has occurred and then runs the
code originally in the timer.
Additional refactoring: Replaced `process.on('exit', ...)` checks with
`common.mustCall()` and replaced usage of `assert.equal()` with
`assert.strictEqual()`.
PR-URL: #10431
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: Trott

…al/test-http-client-timeout-with-data.js …el/test-http-client-timeout-with-data.jstest/sequential/test-http-client-timeout-with-data.js renamed to test/parallel/test-http-client-timeout-with-data.js test/sequential/test-http-client-timeout-with-data.js renamed to test/parallel/test-http-client-timeout-with-data.js

@@ -3,14 +3,8 @@ const common = require('../common');
 constassert=require('assert');
 consthttp=require('http');
 
-varntimeouts=0;
 varnchunks=0;
 
-process.on('exit',function(){
-assert.equal(ntimeouts,1);
-assert.equal(nchunks,2);
-});
-
 constoptions={
 method: 'GET',
 port: undefined,
@@ -21,7 +15,7 @@ const options = {
 constserver=http.createServer(function(req,res){
 res.writeHead(200,{'Content-Length': '2'});
 res.write('*');
-setTimeout(function(){res.end('*');},common.platformTimeout(100));
+server.once('timeout',common.mustCall(function(){res.end('*');}));
 });
 
 server.listen(0,options.host,function(){
@@ -30,19 +24,19 @@ server.listen(0, options.host, function() {
 req.end();
 
 functiononresponse(res){
-req.setTimeout(50,function(){
-assert.equal(nchunks,1);// should have received the first chunk by now
-ntimeouts++;
-});
+req.setTimeout(50,common.mustCall(function(){
+assert.strictEqual(nchunks,1);// should have received the first chunk
+server.emit('timeout');
+}));
 
-res.on('data',function(data){
-assert.equal(''+data,'*');
+res.on('data',common.mustCall(function(data){
+assert.strictEqual(''+data,'*');
 nchunks++;
-});
+},2));
 
-res.on('end',function(){
-assert.equal(nchunks,2);
+res.on('end',common.mustCall(function(){
+assert.strictEqual(nchunks,2);
 server.close();
-});
+}));
 }
 });