feat: only compare enumerable symbols (#91)

Fixes #90.

index.js

@@ -392,8 +392,15 @@ function getEnumerableKeys(target) {
   return keys;
 }
 
-function getNonEnumerableSymbols(target) {
-  var keys = Object.getOwnPropertySymbols(target);
+function getEnumerableSymbols(target) {
+  var keys = [];
+  var allKeys = Object.getOwnPropertySymbols(target);
+  for (var i = 0; i < allKeys.length; i += 1) {
+    var key = allKeys[i];
+    if (Object.getOwnPropertyDescriptor(target, key).enumerable) {
+      keys.push(key);
+    }
+  }
   return keys;
 }
 
@@ -432,8 +439,8 @@ function keysEqual(leftHandOperand, rightHandOperand, keys, options) {
 function objectEqual(leftHandOperand, rightHandOperand, options) {
   var leftHandKeys = getEnumerableKeys(leftHandOperand);
   var rightHandKeys = getEnumerableKeys(rightHandOperand);
-  var leftHandSymbols = getNonEnumerableSymbols(leftHandOperand);
-  var rightHandSymbols = getNonEnumerableSymbols(rightHandOperand);
+  var leftHandSymbols = getEnumerableSymbols(leftHandOperand);
+  var rightHandSymbols = getEnumerableSymbols(rightHandOperand);
   leftHandKeys = leftHandKeys.concat(leftHandSymbols);
   rightHandKeys = rightHandKeys.concat(rightHandSymbols);
 

test/index.js

@@ -444,6 +444,16 @@ describe('Generic', function () {
       objectB = { [symb3]: 'a', [symb2]: 'b' };
       assert(eql(objectA, objectB) === true, 'eql(obj, obj)');
     });
+
+    it('ignores non-enumerable symbols', function () {
+      var symb = Symbol('a');
+      var symb2 = Symbol('b');
+      var objectA = { [symb]: 'a' };
+      Object.defineProperty(objectA, symb2, { value: 'b', enumerable: false });
+      var objectB = { [symb]: 'a' };
+      Object.defineProperty(objectB, symb2, { value: 'c', enumerable: false });
+      assert(eql(objectA, objectB) === true, 'eql(obj, obj)');
+    });
   });