test(NativeArray): Check for cyclic Array.prototype (ref #17190)

jacobq · kategengler · commit b64aa3a7d359 · 2018-12-18T17:28:18.000-05:00
(cherry picked from commit 3029e9d)
diff --git a/packages/@ember/-internals/runtime/tests/array/apply-test.js b/packages/@ember/-internals/runtime/tests/array/apply-test.js
@@ -0,0 +1,34 @@
+import { NativeArray } from '../../lib/mixins/array';
+import { AbstractTestCase, moduleFor } from 'internal-test-helpers';
+
+class ArrayPrototypeExtensionSelfReferenceTests extends AbstractTestCase {
+  '@test should not create non-Symbol, enumerable properties that refer to itself'() {
+    // Don't want to pollute Array.prototype so we make our own to extend
+    class ThrowAwayArray extends Array {}
+
+    // Extend our throw-away prototype (like EXTEND_PROTOTYPES.Array would)
+    NativeArray.apply(ThrowAwayArray.prototype);
+
+    // Create an instance to test
+    let obj = new ThrowAwayArray();
+
+    // Make sure we have an array-like thing & avoid the zero assertion problem is there are no enumerable properties
+    this.assert.strictEqual(obj.length, 0);
+
+    // Make sure that no enumerable properties refer back to the object (creating a cyclic structure)
+    for (let p in obj) {
+      this.assert.notStrictEqual(
+        obj[p],
+        obj,
+        `Property "${p}" is an enumerable part of the prototype
+        so must not refer back to the original array.
+        Otherwise code that explores all properties,
+        such as jQuery.extend and other "deep cloning" functions,
+        will get stuck in an infinite loop.
+        `.replace(/\s+/g, ' ')
+      );
+    }
+  }
+}
+
+moduleFor(`NativeArray: apply`, ArrayPrototypeExtensionSelfReferenceTests);
