fix(orderBy): Mantain order in array of objects when predicate is not provided.

Author: juangabreil

src/ng/filter/orderBy.js

@@ -122,6 +122,7 @@ function orderByFilter($parse){
     sortPredicate = isArray(sortPredicate) ? sortPredicate: [sortPredicate];
     if (sortPredicate.length === 0) { sortPredicate = ['+']; }
     sortPredicate = sortPredicate.map(function(predicate){
+      predicate = predicate || '';
       var descending = false, get = predicate || identity;
       if (isString(predicate)) {
         if ((predicate.charAt(0) == '+' || predicate.charAt(0) == '-')) {
@@ -130,6 +131,12 @@ function orderByFilter($parse){
         }
         if (predicate === '') {
           // Effectively no predicate was passed so we compare identity
+          if (array.some(angular.isObject)) {
+            return function () {
+              return descending ? 1 : 0;
+            };
+          }
+
           return reverseComparator(function(a, b) {
             return compare(a, b);
           }, descending);

test/ng/filter/orderBySpec.js

@@ -91,6 +91,23 @@ describe('Filter: orderBy', function() {
       .toEqualData([{"원": 31000}, {"원": 76000}, {"원": 156000}]);
   });
 
+  it('should maintain order in an array of objects when no predicate is provided', function(){
+      var array = [{a:1}, {b:2}, {c:3}];
+
+      expect(orderBy(array)).toEqualData(array);
+      expect(orderBy(array, '')).toEqualData(array);
+      expect(orderBy(array, [])).toEqualData(array);
+      expect(orderBy(array, [''])).toEqualData(array);
+      expect(orderBy(array, ['+'])).toEqualData(array);
+  });
+
+  it('should inverse order in an array of objects when minus is provided without predicate', function () {
+    var array = [{a: 1}, {b: 2}, {c: 3}],
+        inverseArray = [{c: 3}, {b: 2}, {a: 1}];
+
+    expect(orderBy(array, ['-'])).toEqualData(inverseArray);
+  });
+
   it('should throw if quoted string predicate is quoted incorrectly', function() {
     /*jshint -W008 */
     expect(function() {