test: refactor test-repl-sigint-nested-eval

* remove debugging code that prints child stdout
* indexOf() -> includes()
* improved messages on assertion failures
PR-URL: #11303
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>

Author: Trott

test/parallel/test-repl-sigint-nested-eval.js

@@ -17,18 +17,10 @@ const child = spawn(process.execPath, [ '-i' ], {
 
 letstdout='';
 child.stdout.setEncoding('utf8');
-child.stdout.pipe(process.stdout);
 child.stdout.on('data',function(c){
 stdout+=c;
 });
 
-child.stdin.write=((original)=>{
-return(chunk)=>{
-process.stderr.write(chunk);
-returnoriginal.call(child.stdin,chunk);
-};
-})(child.stdin.write);
-
 child.stdout.once('data',common.mustCall(()=>{
 process.on('SIGUSR2',common.mustCall(()=>{
 process.kill(child.pid,'SIGINT');
@@ -45,6 +37,12 @@ child.stdout.once('data', common.mustCall(() => {
 
 child.on('close',function(code){
 assert.strictEqual(code,0);
-assert.notStrictEqual(stdout.indexOf('Script execution interrupted.'),-1);
-assert.notStrictEqual(stdout.indexOf('foobar'),-1);
+assert.ok(
+stdout.includes('Script execution interrupted.'),
+`Expected stdout to contain "Script execution interrupted.", got ${stdout}`
+);
+assert.ok(
+stdout.includes('foobar'),
+`Expected stdout to contain "foobar", got ${stdout}`
+);
 });