Store Feature: Binding.valEqual +test

Store.js

@@ -678,6 +678,19 @@ HookPrototype.prototype = {
     for( var i = 0, _i = subscribers.length; i < _i; i++ ){
       subscribers[ i ](val);
     }
+  },
+  valEqual: function(compareTo) {
+    var me = this;
+    return function backwardCallback(update) {
+      var cache;
+      me.hook(function(val) {
+        var result = me.equal(val, compareTo);
+        if(result !== cache){
+          cache = result;
+          update(cache);
+        }
+      });
+    }
   }
 };
 var HookFactory = function(accessor, baseObjectCtor) {

test/store.js

@@ -370,3 +370,65 @@ describe('Bug with subscribing to multiple bindings', function() {
         } );
     });
 });
+describe('Feature. Binding.valEqual', function() {
+    it('Should trigger fn when value is changed', function() {
+        var str = new Store.Value.String('123');
+        var changes = [];
+
+        str.valEqual('16')(changes.push.bind(changes));
+        //false +init
+
+        str.set('17');
+        //false
+
+        str.set('123')
+        //false
+
+        str.set('17');
+        //false
+
+        str.set('16');
+        //true +change
+
+        str.set('88')
+        //false +change
+
+        str.set('16');
+        //true +change
+
+        str.set('16');
+        //true
+
+        assert.deepEqual(changes, [false, true, false, true]);
+
+        var str = new Store.Value.String('123');
+        var changes = [];
+
+        str.valEqual('123')(changes.push.bind(changes));
+        //true +init
+
+        str.set('17');
+        //false +change
+
+        str.set('123')
+        //true +change
+
+        str.set('17');
+        //false +change
+
+        str.set('16');
+        //false
+
+        str.set('88')
+        //false
+
+        str.set('16');
+        //false
+
+        str.set('16');
+        //false
+
+        assert.deepEqual(changes, [true, false, true, false]);
+
+    })
+});
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