test: use fs.copyFileSync()

Use the potentially more efficient fs.copyFileSync() instead of reading
the whole file in and writing the whole file out in JavaScript.
PR-URL: #20340
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Khaidi Chu <i@2333.moe>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: richardlau

test/parallel/test-child-process-fork-exec-path.js

@@ -23,6 +23,7 @@
 constcommon=require('../common');
 constassert=require('assert');
 constfs=require('fs');
+const{COPYFILE_FICLONE}=fs.constants;
 constpath=require('path');
 consttmpdir=require('../common/tmpdir');
 constmsg={test: 'this'};
@@ -44,7 +45,7 @@ if (process.env.FORK) {
 }catch(e){
 if(e.code!=='ENOENT')throwe;
 }
-fs.writeFileSync(copyPath,fs.readFileSync(nodePath));
+fs.copyFileSync(nodePath,copyPath,COPYFILE_FICLONE);
 fs.chmodSync(copyPath,'0755');
 
 // slow but simple

test/parallel/test-module-loading-globalpaths.js

@@ -4,6 +4,7 @@ const fixtures = require('../common/fixtures');
 constassert=require('assert');
 constpath=require('path');
 constfs=require('fs');
+const{COPYFILE_FICLONE}=fs.constants;
 constchild_process=require('child_process');
 constpkgName='foo';
 const{ addLibraryPath }=require('../common/shared-lib-util');
@@ -28,7 +29,7 @@ if (process.argv[2] === 'child') {
 testExecPath=path.join(prefixBinPath,path.basename(process.execPath));
 }
 constmode=fs.statSync(process.execPath).mode;
-fs.writeFileSync(testExecPath,fs.readFileSync(process.execPath));
+fs.copyFileSync(process.execPath,testExecPath,COPYFILE_FICLONE);
 fs.chmodSync(testExecPath,mode);
 
 construnTest=(expectedString,env)=>{