Make toEqual matcher report the difference between objects

- Mismatches deep within object/array structures are pinpointed with a JsonPath-like syntax.

spec/core/UtilSpec.js

@@ -63,4 +63,37 @@ describe("jasmineUnderTest.util", function() {
       expect(actual).toEqual(expected);
     });
   });
+
+  describe("objectDifference", function() {
+    it("given two objects A and B, returns the properties in A not present in B", function() {
+      var a = {
+        foo: 3,
+        bar: 4,
+        baz: 5
+      };
+
+      var b = {
+        bar: 6,
+        quux: 7
+      };
+
+      expect(jasmineUnderTest.util.objectDifference(a, b)).toEqual({foo: 3, baz: 5})
+    });
+
+    it("only looks at own properties of both objects", function() {
+      function Foo() {}
+
+      Foo.prototype.x = 1;
+      Foo.prototype.y = 2;
+
+      var a = new Foo();
+      a.x = 1;
+
+      var b = new Foo();
+      b.y = 2;
+
+      expect(jasmineUnderTest.util.objectDifference(a, b)).toEqual({x: 1});
+      expect(jasmineUnderTest.util.objectDifference(b, a)).toEqual({y: 2});
+    })
+  })
 });