test: fix race condition in test-child-process-bad-stdio

test-child-process-bad-stdio.js contains a race condition between
a timeout in the test process and a timeout in the spawned child
process. This commit addresses the race condition by having the
child process wait indefinitely to be killed.

Author: cjihrig

test/parallel/test-child-process-bad-stdio.js

@@ -2,11 +2,16 @@
 // Flags: --expose-internals
 const common = require('../common');
 
-if (process.argv[2] === 'child') {
+if (process.argv[2] === 'timeout') {
   setTimeout(() => {}, common.platformTimeout(100));
   return;
 }
 
+if (process.argv[2] === 'interval') {
+  setInterval(() => {}, 10_000);
+  return;
+}
+
 const assert = require('node:assert');
 const cp = require('node:child_process');
 const { mock, test } = require('node:test');
@@ -29,7 +34,8 @@ mock.method(ChildProcess.prototype, 'spawn', function() {
 });
 
 function createChild(options, callback) {
-  const [cmd, opts] = common.escapePOSIXShell`"${process.execPath}" "${__filename}" child`;
+  const childType = options.child ?? 'timeout';
+  const [cmd, opts] = common.escapePOSIXShell`"${process.execPath}" "${__filename}" ${childType}`;
   options = { ...options, env: { ...opts?.env, ...options.env } };
 
   return cp.exec(cmd, options, common.mustCall(callback));
@@ -57,7 +63,8 @@ test('execution with an error event is handled', (_, done) => {
 });
 
 test('execution with a killed process is handled', (_, done) => {
-  createChild({ timeout: 1 }, (err, stdout, stderr) => {
+  const timeout = common.platformTimeout(100);
+  createChild({ child: 'interval', timeout }, (err, stdout, stderr) => {
     assert.strictEqual(err.killed, true);
     assert.strictEqual(stdout, '');
     assert.strictEqual(stderr, '');