test: added input validation test for fchmod

Added a test to ensure input validation for FD and mode for fs.fchmod.
Removed check for values lower than 0 for `mode` as it's already checked
by `validateUint32`.

PR-URL: https://github.com/nodejs/node/pull/18217
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

lib/fs.js

@@ -1340,7 +1340,8 @@ fs.fchmod = function(fd, mode, callback) {
   mode = modeNum(mode);
   validateUint32(fd, 'fd');
   validateUint32(mode, 'mode');
-  if (mode < 0 || mode > 0o777)
+  // values for mode < 0 are already checked via the validateUint32 function
+  if (mode > 0o777)
     throw new errors.RangeError('ERR_OUT_OF_RANGE', 'mode');
 
   const req = new FSReqWrap();

test/parallel/test-fs-fchmod.js

@@ -0,0 +1,67 @@
+'use strict';
+const common = require('../common');
+const fs = require('fs');
+
+// This test ensures that input for fchmod is valid, testing for valid
+// inputs for fd and mode
+
+// Check input type
+['', false, null, undefined, {}, [], Infinity, -1].forEach((i) => {
+  common.expectsError(
+    () => fs.fchmod(i),
+    {
+      code: 'ERR_INVALID_ARG_TYPE',
+      type: TypeError,
+      message: 'The "fd" argument must be of type integer'
+    }
+  );
+  common.expectsError(
+    () => fs.fchmodSync(i),
+    {
+      code: 'ERR_INVALID_ARG_TYPE',
+      type: TypeError,
+      message: 'The "fd" argument must be of type integer'
+    }
+  );
+
+  common.expectsError(
+    () => fs.fchmod(1, i),
+    {
+      code: 'ERR_INVALID_ARG_TYPE',
+      type: TypeError,
+      message: 'The "mode" argument must be of type integer'
+    }
+  );
+  common.expectsError(
+    () => fs.fchmodSync(1, i),
+    {
+      code: 'ERR_INVALID_ARG_TYPE',
+      type: TypeError,
+      message: 'The "mode" argument must be of type integer'
+    }
+  );
+});
+
+// Check for mode values range
+const modeUpperBoundaryValue = 0o777;
+fs.fchmod(1, modeUpperBoundaryValue);
+fs.fchmodSync(1, modeUpperBoundaryValue);
+
+// umask of 0o777 is equal to 775
+const modeOutsideUpperBoundValue = 776;
+common.expectsError(
+  () => fs.fchmod(1, modeOutsideUpperBoundValue),
+  {
+    code: 'ERR_OUT_OF_RANGE',
+    type: RangeError,
+    message: 'The value of "mode" is out of range.'
+  }
+);
+common.expectsError(
+  () => fs.fchmodSync(1, modeOutsideUpperBoundValue),
+  {
+    code: 'ERR_OUT_OF_RANGE',
+    type: RangeError,
+    message: 'The value of "mode" is out of range.'
+  }
+);

test/parallel/test-fs-fchown.js

@@ -3,7 +3,7 @@
 const common = require('../common');
 const fs = require('fs');
 
-['', false, null, undefined, {}, []].forEach((i) => {
+['', false, null, undefined, {}, [], Infinity, -1].forEach((i) => {
   common.expectsError(
     () => fs.fchown(i),
     {