1 files changed, 34 insertions, 0 deletions
diff --git a/js/src/tests/non262/Array/concat-spreadable-primitive.js b/js/src/tests/non262/Array/concat-spreadable-primitive.js
new file mode 100644
index 0000000000..d2264bfa2a
--- /dev/null
+++ b/js/src/tests/non262/Array/concat-spreadable-primitive.js
@@ -0,0 +1,34 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/ */
+"use strict";
+
+// Primitive values should never be tried to spread
+let primitives = [
+    10,
+    false,
+    Symbol()
+    // Can't change String.prototype.length
+];
+
+for (let value of primitives) {
+    let prototype = Object.getPrototypeOf(value);
+    prototype[Symbol.isConcatSpreadable] = true;
+
+    Object.defineProperty(prototype, "length", {
+        configurable: true,
+        get() {
+            // Should never invoke length getter
+            assertEq(true, false);
+        },
+    });
+
+    let x = [1, 2].concat(value);
+    assertDeepEq(x, [1, 2, value]);
+
+    delete prototype[Symbol.isConcatSpreadable];
+    delete prototype.length;
+
+    prototype.length;
+}
+
+reportCompare(true, true);