From fb8365b1697508021501c933ce10876e33748c99 Mon Sep 17 00:00:00 2001
From: Daeyeon Jeong <daeyeon.dev@gmail.com>
Date: Thu, 14 Apr 2022 10:13:24 +0900
Subject: [PATCH 1/6] child_process: add hasRef to ChildProcess

Refs: https://github.com/nodejs/node/issues/42091

The issue above reported a specific use case about `hasRef()`.
After reading the issue, I started thinking users may naturally expect
`hasRef` method if `ref()` and `unref()` exist on an object they use.
As of now, however, `hasRef()` exists on `Timer` only.

This commit suggests adding `hasRef` method to `ChildProcess` first.
There are more similar cases. (fs.FSWatcher, fs.StatWatcher, net.Socket,
and so on)
---
 doc/api/child_process.md                   | 26 +++++++++++++++++++
 lib/internal/child_process.js              |  5 ++++
 test/parallel/test-child-process-hasref.js | 30 ++++++++++++++++++++++
 3 files changed, 61 insertions(+)
 create mode 100644 test/parallel/test-child-process-hasref.js

diff --git a/doc/api/child_process.md b/doc/api/child_process.md
index ad712eb8786f59..e30576aea75ee3 100644
--- a/doc/api/child_process.md
+++ b/doc/api/child_process.md
@@ -1434,6 +1434,32 @@ console.log(`Spawned child pid: ${grep.pid}`);
 grep.stdin.end();
 ```
 
+### `subprocess.hasRef()`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* Returns: {boolean}
+
+Indicates whether a `subprocess` is "ref'ed" by the parent process's event
+loop. If `true`, the parent waits for the child to exit before exiting itself.
+
+```js
+const { spawn } = require('child_process');
+
+const subprocess = spawn(process.argv[0], ['child_program.js'], {
+  detached: true,
+  stdio: 'ignore',
+});
+
+subprocess.on('exit', (code) => {
+  subprocess.hasRef(); // false
+});
+
+subprocess.hasRef(); // true
+```
+
 ### `subprocess.ref()`
 
 <!-- YAML
diff --git a/lib/internal/child_process.js b/lib/internal/child_process.js
index 0e4cfc2ead2bf4..cbe1cfa5087a14 100644
--- a/lib/internal/child_process.js
+++ b/lib/internal/child_process.js
@@ -519,6 +519,11 @@ ChildProcess.prototype.unref = function() {
   if (this._handle) this._handle.unref();
 };
 
+
+ChildProcess.prototype.hasRef = function() {
+  return this._handle ? this._handle.hasRef() : false;
+};
+
 class Control extends EventEmitter {
   #channel = null;
   #refs = 0;
diff --git a/test/parallel/test-child-process-hasref.js b/test/parallel/test-child-process-hasref.js
new file mode 100644
index 00000000000000..bfdebce707fbad
--- /dev/null
+++ b/test/parallel/test-child-process-hasref.js
@@ -0,0 +1,30 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const { spawn, ChildProcess } = require('child_process');
+
+const command = common.isWindows ? 'dir' : 'ls';
+const child = spawn(command);
+
+assert.strictEqual(child.hasRef(), true);
+
+child.unref();
+assert.strictEqual(child.hasRef(), false);
+
+child.ref();
+assert.strictEqual(child.hasRef(), true);
+
+function mustHasRef() {
+  return common.mustCall(() => assert.strictEqual(child.hasRef(), true));
+}
+
+function mustHasNoRef() {
+  return common.mustCall(() => assert.strictEqual(child.hasRef(), false));
+}
+
+child.stdout.on('data', mustHasRef());
+child.stdout.on('end', mustHasRef());
+child.stdout.on('close', mustHasNoRef());
+child.on('exit', mustHasNoRef());
+child.on('close', mustHasNoRef());

From 1f500a33ab9640ab6f4f64b24d02c83e24571982 Mon Sep 17 00:00:00 2001
From: Daeyeon Jeong <daeyeon.dev@gmail.com>
Date: Thu, 14 Apr 2022 17:46:46 +0900
Subject: [PATCH 2/6] fix: lint-js error

---
 test/parallel/test-child-process-hasref.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/parallel/test-child-process-hasref.js b/test/parallel/test-child-process-hasref.js
index bfdebce707fbad..eba640f438756a 100644
--- a/test/parallel/test-child-process-hasref.js
+++ b/test/parallel/test-child-process-hasref.js
@@ -2,7 +2,7 @@
 
 const common = require('../common');
 const assert = require('assert');
-const { spawn, ChildProcess } = require('child_process');
+const { spawn } = require('child_process');
 
 const command = common.isWindows ? 'dir' : 'ls';
 const child = spawn(command);

From 3cd3796c5d7a11d40ec074becb597a11806084f6 Mon Sep 17 00:00:00 2001
From: Daeyeon Jeong <daeyeon.dev@gmail.com>
Date: Thu, 14 Apr 2022 21:01:06 +0900
Subject: [PATCH 3/6] fix: update the tc

This removes assertions where the child could be {un}referred.
---
 test/parallel/test-child-process-hasref.js | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/test/parallel/test-child-process-hasref.js b/test/parallel/test-child-process-hasref.js
index eba640f438756a..fd8541a4c3539f 100644
--- a/test/parallel/test-child-process-hasref.js
+++ b/test/parallel/test-child-process-hasref.js
@@ -15,16 +15,12 @@ assert.strictEqual(child.hasRef(), false);
 child.ref();
 assert.strictEqual(child.hasRef(), true);
 
-function mustHasRef() {
-  return common.mustCall(() => assert.strictEqual(child.hasRef(), true));
-}
-
-function mustHasNoRef() {
-  return common.mustCall(() => assert.strictEqual(child.hasRef(), false));
-}
-
-child.stdout.on('data', mustHasRef());
-child.stdout.on('end', mustHasRef());
-child.stdout.on('close', mustHasNoRef());
-child.on('exit', mustHasNoRef());
-child.on('close', mustHasNoRef());
+child.on(
+  'exit',
+  common.mustCall(() => assert.strictEqual(child.hasRef(), false)),
+);
+
+child.on(
+  'close',
+  common.mustCall(() => assert.strictEqual(child.hasRef(), false)),
+);

From e8b3ef39df605f2ae1e8bc762cab2a7835bc0ea1 Mon Sep 17 00:00:00 2001
From: Daeyeon Jeong <daeyeon.dev@gmail.com>
Date: Sat, 16 Apr 2022 10:28:01 +0900
Subject: [PATCH 4/6] fix: simplify code

---
 lib/internal/child_process.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/internal/child_process.js b/lib/internal/child_process.js
index cbe1cfa5087a14..7154a3280fd51e 100644
--- a/lib/internal/child_process.js
+++ b/lib/internal/child_process.js
@@ -521,7 +521,7 @@ ChildProcess.prototype.unref = function() {
 
 
 ChildProcess.prototype.hasRef = function() {
-  return this._handle ? this._handle.hasRef() : false;
+  return !!this._handle?.hasRef();
 };
 
 class Control extends EventEmitter {

From fd8a0518e4cc24bb9a51c83ccf2afe3e28027b3e Mon Sep 17 00:00:00 2001
From: Daeyeon Jeong <daeyeon.dev@gmail.com>
Date: Sat, 16 Apr 2022 23:28:36 +0900
Subject: [PATCH 5/6] fix: add stability level

---
 doc/api/child_process.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/doc/api/child_process.md b/doc/api/child_process.md
index e30576aea75ee3..079a8f9605f5be 100644
--- a/doc/api/child_process.md
+++ b/doc/api/child_process.md
@@ -1440,6 +1440,8 @@ grep.stdin.end();
 added: REPLACEME
 -->
 
+> Stability: 1 - Experimental
+
 * Returns: {boolean}
 
 Indicates whether a `subprocess` is "ref'ed" by the parent process's event

From 0318f8f920d4963e8289815ccc78129f51646669 Mon Sep 17 00:00:00 2001
From: Daeyeon Jeong <daeyeon.dev@gmail.com>
Date: Sat, 16 Apr 2022 23:48:53 +0900
Subject: [PATCH 6/6] fix: add `node:` prefix

---
 doc/api/child_process.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/api/child_process.md b/doc/api/child_process.md
index 079a8f9605f5be..c90e206ca77cda 100644
--- a/doc/api/child_process.md
+++ b/doc/api/child_process.md
@@ -1448,7 +1448,7 @@ Indicates whether a `subprocess` is "ref'ed" by the parent process's event
 loop. If `true`, the parent waits for the child to exit before exiting itself.
 
 ```js
-const { spawn } = require('child_process');
+const { spawn } = require('node:child_process');
 
 const subprocess = spawn(process.argv[0], ['child_program.js'], {
   detached: true,