Object.assign: Make sure non-enumerable Symbols are excluded.

Per dc23efa#commitcomment-10684061 and https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.assign step 5.c.iii
paulmillr · Apr 12, 2015 · db7d6a4 · db7d6a4
1 parent fa3ca7d
commit db7d6a4
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Showing 2 changed files with 13 additions and 6 deletions.
diff --git a/es6-shim.js b/es6-shim.js
@@ -935,10 +935,14 @@
   });
 
   if (supportsDescriptors) {
+    var isEnumerableOn = Function.bind.call(Function.bind, Object.prototype.propertyIsEnumerable);
     var assignReducer = function (target, source) {
       var keys = Object.keys(Object(source));
-      var symbols = ES.IsCallable(Object.getOwnPropertySymbols) ? Object.getOwnPropertySymbols(Object(source)) : [];
-      return keys.concat(symbols).reduce(function (target, key) {
+      var symbols;
+      if (ES.IsCallable(Object.getOwnPropertySymbols)) {
+        symbols = Object.getOwnPropertySymbols(Object(source)).filter(isEnumerableOn(source));
+      }
+      return keys.concat(symbols || []).reduce(function (target, key) {
         target[key] = source[key];
         return target;
       }, target);

diff --git a/test/object.js b/test/object.js
@@ -220,16 +220,19 @@ describe('Object', function () {
       expect(thrower).to.have.property(1, 2);
     });
 
-    ifSymbolsIt('includes symbols, after keys', function () {
+    ifSymbolsIt('includes enumerable symbols, after keys', function () {
       var visited = [];
       var obj = {};
       Object.defineProperty(obj, 'a', { get: function () { visited.push('a'); return 42; }, enumerable: true });
-      var symbol = Symbol();
+      var symbol = Symbol('enumerable');
       Object.defineProperty(obj, symbol, { get: function () { visited.push(symbol); return Infinity; }, enumerable: true });
+      var nonEnumSymbol = Symbol('non-enumerable');
+      Object.defineProperty(obj, nonEnumSymbol, { get: function () { visited.push(nonEnumSymbol); return -Infinity; }, enumerable: false });
       var target = Object.assign({}, obj);
-      expect(target[symbol]).to.equal(Infinity);
-      expect(target.a).to.equal(42);
       expect(visited).to.eql(['a', symbol]);
+      expect(target.a).to.equal(42);
+      expect(target[symbol]).to.equal(Infinity);
+      expect(target[nonEnumSymbol]).not.to.equal(-Infinity);
     });
   });