os: add os.devnull()

Returns the platform-specific file path of the null device.

Author: lpinca

doc/api/os.md

@@ -122,6 +122,18 @@ The properties included on each object include:
 `nice` values are POSIX-only. On Windows, the `nice` values of all processors
 are always 0.
 
+## `os.devnull()`
+<!-- YAML
+added: REPLACEME
+-->
+
+* Returns: {string}
+
+Returns the platform-specific file path of the null device:
+
+* `\\.\nul` on Windows
+* `/dev/null` on POSIX
+
 ## `os.endianness()`
 <!-- YAML
 added: v0.9.4

doc/api/path.md

@@ -135,18 +135,6 @@ process.env.PATH.split(path.delimiter);
 // Returns ['C:\\Windows\\system32', 'C:\\Windows', 'C:\\Program Files\\node\\']
 ```
 
-## `path.devnull`
-<!-- YAML
-added: REPLACEME
--->
-
-* {string}
-
-Provides the platform-specific file path of the null device:
-
-* `\\.\nul` on Windows
-* `/dev/null` on POSIX
-
 ## `path.dirname(path)`
 <!-- YAML
 added: v0.1.16

lib/os.js

@@ -349,9 +349,18 @@ function userInfo(options) {
   return user;
 }
 
+/**
+ * @returns {string}
+ */
+function devnull() {
+  return isWindows ? '\\\\.\\nul' : '/dev/null';
+}
+devnull[SymbolToPrimitive] = () => devnull();
+
 module.exports = {
   arch,
   cpus,
+  devnull,
   endianness,
   freemem: getFreeMem,
   getPriority,

lib/path.js

@@ -1065,7 +1065,6 @@ const win32 = {
     return ret;
   },
 
-  devnull: '\\\\.\\nul',
   sep: '\\',
   delimiter: ';',
   win32: null,
@@ -1532,7 +1531,6 @@ const posix = {
     return ret;
   },
 
-  devnull: '/dev/null',
   sep: '/',
   delimiter: ':',
   win32: null,

test/parallel/test-os.js

@@ -259,3 +259,13 @@ if (!common.isIBMi) {
 
 is.number(+os.freemem, 'freemem');
 is.number(os.freemem(), 'freemem');
+
+const devnull = os.devnull();
+
+if (common.isWindows) {
+  assert.strictEqual(devnull, '\\\\.\\nul');
+} else {
+  assert.strictEqual(devnull, '/dev/null');
+}
+
+assert.strictEqual(`${os.devnull}`, devnull);

test/parallel/test-path.js

@@ -67,12 +67,6 @@ assert.strictEqual(path.win32.delimiter, ';');
 // posix
 assert.strictEqual(path.posix.delimiter, ':');
 
-// path.devnull tests
-// windows
-assert.strictEqual(path.win32.devnull, '\\\\.\\nul');
-// posix
-assert.strictEqual(path.posix.devnull, '/dev/null');
-
 if (common.isWindows)
   assert.strictEqual(path, path.win32);
 else