Fixed Issue #483 for a test done for fs.mknod promise (#509)

* test done for fs.mknod promise

* fixing whitespaces

tests/spec/fs.mknod.spec.js

@@ -79,4 +79,15 @@ describe('fs.mknod', function() {
       });
     });
   });
+  describe('Promise test mknod', function(){
+
+    it('should return an error if part of the parent path does not exist', function(){
+      var fs = util.fs().promises;
+
+      return fs.mknod('/dir/mydir', 'DIRECTORY')
+        .catch(error => {
+          expect(error.code).to.equal('ENOENT');
+        });
+    });
+  });
 });