Add proper object conversion to updated diff

src/updated/index.js

@@ -1,20 +1,23 @@
-import { isDate, isEmpty, isObject } from '../utils';
+import { isDate, isEmpty, isObject, properObject } from '../utils';
 
 const updatedDiff = (lhs, rhs) => {
 
   if (lhs === rhs) return {};
 
   if (!isObject(lhs) || !isObject(rhs)) return rhs;
 
-  if (isDate(lhs) || isDate(rhs)) {
-    if (lhs.toString() == rhs.toString()) return {};
-    return rhs;
+  const l = properObject(lhs);
+  const r = properObject(rhs);
+
+  if (isDate(l) || isDate(r)) {
+    if (l.toString() == r.toString()) return {};
+    return r;
   }
 
-  return Object.keys(rhs).reduce((acc, key) => {
+  return Object.keys(r).reduce((acc, key) => {
 
-    if (lhs.hasOwnProperty(key)) {
-      const difference = updatedDiff(lhs[key], rhs[key]);
+    if (l.hasOwnProperty(key)) {
+      const difference = updatedDiff(l[key], r[key]);
 
       if (isObject(difference) && isEmpty(difference) && !isDate(difference)) return acc;
 

src/updated/index.test.js

@@ -103,5 +103,41 @@ describe('.updatedDiff', () => {
         expect(updatedDiff(new Date('2016'), new Date('2016'))).toEqual({});
       });
     });
+
+    describe('object create null', () => {
+      test('returns right hand side value when given objects are different at root', () => {
+        const lhs = Object.create(null);
+        lhs.a = 1;
+        const rhs = Object.create(null);
+        rhs.a = 2;
+        expect(updatedDiff(lhs, rhs)).toEqual({ a: 2 });
+      });
+
+      test('returns subset of right hand side value when sibling objects differ', () => {
+        const lhs = Object.create(null);
+        lhs.a = { b: 1 };
+        lhs.c = 2;
+        const rhs = Object.create(null);
+        rhs.a = { b: 1 };
+        rhs.c = 3;
+        expect(updatedDiff(lhs, rhs)).toEqual({ c: 3 });
+      });
+
+      test('returns subset of right hand side value when nested values differ', () => {
+        const lhs = Object.create(null);
+        lhs.a = { b: 1, c: 2 };
+        const rhs = Object.create(null);
+        rhs.a = { b: 1, c: 3 };
+        expect(updatedDiff(lhs, rhs)).toEqual({ a: { c: 3 } });
+      });
+
+      test('returns subset of right hand side with updated date', () => {
+        const lhs = Object.create(null);
+        lhs.date = new Date('2016');
+        const rhs = Object.create(null);
+        rhs.date = new Date('2017');
+        expect(updatedDiff(lhs, rhs)).toEqual({ date: new Date('2017') });
+      });
+    });
   });
 });