test: improve coverage for process.umask

This ensures that process.umask() throws with the correct error when
invalid inputs are supplied.

PR-URL: #16188
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Tobias Nießen <[email protected]>
Reviewed-By: Jeremiah Senkpiel <[email protected]>
Reviewed-By: Yuta Hiroto <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>

Author: evanlucas

test/parallel/test-umask.js

@@ -19,3 +19,11 @@ assert.strictEqual(parseInt(mask, 8), process.umask(old));
 assert.strictEqual(old, process.umask());
 // 2. If the test fails, process.umask() will return 0
 assert.strictEqual(old, process.umask());
+
+assert.throws(() => {
+  process.umask({});
+}, /argument must be an integer or octal string/);
+
+assert.throws(() => {
+  process.umask('123x');
+}, /invalid octal string/);