test: refactor test-stream-unshift-read-race

* add RegExp as second argument to assert.throws()
* replace process.on('exit', ...) boolean checks with common.mustCall()
* assert.equal() -> assert.strictEqual()
* add 1 ms duration as second argument to setTimeout()
* var -> const
PR-URL: #10532
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: Trott

test/parallel/test-stream-unshift-read-race.js

@@ -1,6 +1,6 @@
 'use strict';
-require('../common');
-varassert=require('assert');
+constcommon=require('../common');
+constassert=require('assert');
 
 // This test verifies that:
 // 1. unshift() does not cause colliding _read() calls.
@@ -9,19 +9,19 @@ var assert = require('assert');
 // 3. push() after the EOF signaling null is an error.
 // 4. _read() is not called after pushing the EOF null chunk.
 
-varstream=require('stream');
-varhwm=10;
-varr=stream.Readable({highWaterMark: hwm});
-varchunks=10;
+conststream=require('stream');
+consthwm=10;
+constr=stream.Readable({highWaterMark: hwm});
+constchunks=10;
 
-vardata=Buffer.allocUnsafe(chunks*hwm+Math.ceil(hwm/2));
-for(vari=0;i<data.length;i++){
-varc='asdf'.charCodeAt(i%4);
+constdata=Buffer.allocUnsafe(chunks*hwm+Math.ceil(hwm/2));
+for(leti=0;i<data.length;i++){
+constc='asdf'.charCodeAt(i%4);
 data[i]=c;
 }
 
-varpos=0;
-varpushedNull=false;
+letpos=0;
+letpushedNull=false;
 r._read=function(n){
 assert(!pushedNull,'_read after null push');
 
@@ -30,7 +30,7 @@ r._read = function(n) {
 
 functionpush(fast){
 assert(!pushedNull,'push() after null push');
-varc=pos>=data.length ? null : data.slice(pos,pos+n);
+constc=pos>=data.length ? null : data.slice(pos,pos+n);
 pushedNull=c===null;
 if(fast){
 pos+=n;
@@ -41,59 +41,54 @@ r._read = function(n) {
 pos+=n;
 r.push(c);
 if(c===null)pushError();
-});
+},1);
 }
 }
 };
 
 functionpushError(){
 assert.throws(function(){
 r.push(Buffer.allocUnsafe(1));
-});
+},/^Error:stream.push\(\)afterEOF$/);
 }
 
 
-varw=stream.Writable();
-varwritten=[];
+constw=stream.Writable();
+constwritten=[];
 w._write=function(chunk,encoding,cb){
 written.push(chunk.toString());
 cb();
 };
 
-varended=false;
-r.on('end',function(){
-assert(!ended,'end emitted more than once');
+r.on('end',common.mustCall(function(){
 assert.throws(function(){
 r.unshift(Buffer.allocUnsafe(1));
-});
-ended=true;
+},/^Error:stream.unshift\(\)afterendevent$/);
 w.end();
-});
+}));
 
 r.on('readable',function(){
-varchunk;
+letchunk;
 while(null!==(chunk=r.read(10))){
 w.write(chunk);
 if(chunk.length>4)
 r.unshift(Buffer.from('1234'));
 }
 });
 
-varfinished=false;
-w.on('finish',function(){
-finished=true;
+w.on('finish',common.mustCall(function(){
 // each chunk should start with 1234, and then be asfdasdfasdf...
 // The first got pulled out before the first unshift('1234'), so it's
 // lacking that piece.
-assert.equal(written[0],'asdfasdfas');
-varasdf='d';
+assert.strictEqual(written[0],'asdfasdfas');
+letasdf='d';
 console.error('0: %s',written[0]);
-for(vari=1;i<written.length;i++){
+for(leti=1;i<written.length;i++){
 console.error('%s: %s',i.toString(32),written[i]);
-assert.equal(written[i].slice(0,4),'1234');
-for(varj=4;j<written[i].length;j++){
-varc=written[i].charAt(j);
-assert.equal(c,asdf);
+assert.strictEqual(written[i].slice(0,4),'1234');
+for(letj=4;j<written[i].length;j++){
+constc=written[i].charAt(j);
+assert.strictEqual(c,asdf);
 switch(asdf){
 case'a': asdf='s';break;
 case's': asdf='d';break;
@@ -102,11 +97,9 @@ w.on('finish', function() {
 }
 }
 }
-});
+}));
 
 process.on('exit',function(){
-assert.equal(written.length,18);
-assert(ended,'stream ended');
-assert(finished,'stream finished');
+assert.strictEqual(written.length,18);
 console.log('ok');
 });