feat(filter): allow map of filters to be registered

This feature adds similar functionality to what `$ControllerProvider.register`
and `$CompileProvider.directive` currently provide by allowing a map of filter
name/factories to be passed as the sole argument to `$FilterProvider.register`
to register all of the specified filters.

Closes #4036
Closes #4091

src/ng/filter.js

@@ -78,15 +78,32 @@ $FilterProvider.$inject = ['$provide'];
 function $FilterProvider($provide) {
   var suffix = 'Filter';
 
+  /**
+   * @ngdoc function
+   * @name ng.$controllerProvider#register
+   * @methodOf ng.$controllerProvider
+   * @param {string|Object} name Name of the filter function, or an object map of filters where
+   *    the keys are the filter names and the values are the filter factories.
+   * @returns {Object} Registered filter instance, or if a map of filters was provided then a map
+   *    of the registered filter instances.
+   */
   function register(name, factory) {
-    return $provide.factory(name + suffix, factory);
+    if(isObject(name)) {
+      var filters = {};
+      forEach(name, function(filter, key) {
+        filters[key] = register(key, filter);
+      });
+      return filters;
+    } else {
+      return $provide.factory(name + suffix, factory);
+    }
   }
   this.register = register;
 
   this.$get = ['$injector', function($injector) {
     return function(name) {
       return $injector.get(name + suffix);
-    }
+    };
   }];
 
   ////////////////////////////////////////

test/ng/filterSpec.js

@@ -0,0 +1,47 @@
+'use strict';
+
+describe('$filter', function() {
+  var $filterProvider, $filter;
+
+  beforeEach(module(function(_$filterProvider_) {
+    $filterProvider = _$filterProvider_;
+  }));
+
+  beforeEach(inject(function(_$filter_) {
+    $filter = _$filter_;
+  }));
+
+  describe('provider', function() {
+    it('should allow registration of filters', function() {
+      var FooFilter = function() {
+        return function() { return 'foo'; };
+      };
+
+      $filterProvider.register('foo', FooFilter);
+
+      var fooFilter = $filter('foo');
+      expect(fooFilter()).toBe('foo');
+    });
+
+    it('should allow registration of a map of filters', function() {
+      var FooFilter = function() {
+        return function() { return 'foo'; };
+      };
+
+      var BarFilter = function() {
+        return function() { return 'bar'; };
+      };
+
+      $filterProvider.register({
+        'foo': FooFilter,
+        'bar': BarFilter
+      });
+
+      var fooFilter = $filter('foo');
+      expect(fooFilter()).toBe('foo');
+
+      var barFilter = $filter('bar');
+      expect(barFilter()).toBe('bar');
+    });
+  });
+});