Fix: Symbol based properties in arrays causes toEqual to throw

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## master
 
+### Fixes
+
+- `[expect]` Using symbolic property names in arrays no longer causes the `toEqual` matcher to fail ([#6391](https://github.com/facebook/jest/pull/6391))
+
 ## 23.1.0
 
 ### Features

packages/expect/src/__tests__/matchers.test.js

@@ -442,6 +442,19 @@ describe('.toEqual()', () => {
       );
     }
   });
+
+  test('symbol based keys in arrays are processed correctly', () => {
+    const mySymbol = Symbol('test');
+    const actual1 = [];
+    actual1[mySymbol] = 3;
+    const actual2 = [];
+    actual2[mySymbol] = 4;
+    const expected = [];
+    expected[mySymbol] = 3;
+
+    expect(actual1).toEqual(expected);
+    expect(actual2).not.toEqual(expected);
+  });
 });
 
 describe('.toBeInstanceOf()', () => {

packages/expect/src/jasmine_utils.js

@@ -222,7 +222,8 @@ function keys(obj, isArray, hasKey) {
   }
 
   for (var x = 0; x < allKeys.length; x++) {
-    if (!allKeys[x].match(/^[0-9]+$/)) {
+    //$FlowFixMe
+    if (typeof allKeys[x] === 'symbol' || !allKeys[x].match(/^[0-9]+$/)) {
       extraKeys.push(allKeys[x]);
     }
   }