test: refactor test-stream-big-push

* use common.mustCall()
* specify setTimeout() duration of 1ms
* remove unused `n` function argument
PR-URL: #10226
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

Author: Trott

test/parallel/test-stream-big-push.js

@@ -1,5 +1,5 @@
 'use strict';
-require('../common');
+constcommon=require('../common');
 constassert=require('assert');
 conststream=require('stream');
 conststr='asdfasdfasdfasdfasdf';
@@ -10,29 +10,25 @@ const r = new stream.Readable({
 });
 
 letreads=0;
-leteofed=false;
-letended=false;
 
-r._read=function(n){
+function_read(){
 if(reads===0){
 setTimeout(function(){
 r.push(str);
-});
+},1);
 reads++;
 }elseif(reads===1){
 varret=r.push(str);
 assert.strictEqual(ret,false);
 reads++;
 }else{
-assert(!eofed);
-eofed=true;
 r.push(null);
 }
-};
+}
 
-r.on('end',function(){
-ended=true;
-});
+r._read=common.mustCall(_read,3);
+
+r.on('end',common.mustCall(function(){}));
 
 // push some data in to start.
 // we've never gotten any read event at this point.
@@ -55,10 +51,3 @@ r.once('readable', function() {
 chunk=r.read();
 assert.strictEqual(chunk,null);
 });
-
-process.on('exit',function(){
-assert(eofed);
-assert(ended);
-assert.strictEqual(reads,2);
-console.log('ok');
-});