fix objectGuard edge case: null values

Author: dgirardi

libraries/objectGuard/objectGuard.js

@@ -92,7 +92,7 @@ export function writeProtectRule(ruleDef) {
     run(root, path, object, property, applies) {
       const origHasProp = object && object.hasOwnProperty(property);
       const original = origHasProp ? object[property] : undefined;
-      const origCopy = origHasProp && typeof original === 'object' ? deepClone(original) : original;
+      const origCopy = origHasProp && original != null && typeof original === 'object' ? deepClone(original) : original;
       return function () {
         const object = path == null ? root : deepAccess(root, path);
         const finalHasProp = object && isData(object[property]);

test/spec/activities/objectGuard_spec.js

@@ -122,14 +122,23 @@ describe('objectGuard', () => {
           }
         }
       })
-    })
+    });
+
     it('should undo nested deletes', () => {
       const obj = {outer: {inner: {foo: {nested: 'val'}, bar: 'val'}}};
       const guard = objectGuard([rule])(obj);
       delete guard.obj.outer.inner.foo.nested;
       delete guard.obj.outer.inner.bar;
       guard.verify();
       expect(obj).to.eql({outer: {inner: {foo: {nested: 'val'}, bar: 'val'}}})
-    })
+    });
+
+    it('should work on null properties', () => {
+      const obj = {foo: null};
+      const guard = objectGuard([rule])(obj);
+      guard.obj.foo = 'denied';
+      guard.verify();
+      expect(obj).to.eql({foo: null});
+    });
   });
 });