1 files changed, 37 insertions, 0 deletions
diff --git a/js/src/tests/ecma_6/Array/concat-spreadable-basic.js b/js/src/tests/ecma_6/Array/concat-spreadable-basic.js
new file mode 100644
index 000000000..c13f8f5cd
--- /dev/null
+++ b/js/src/tests/ecma_6/Array/concat-spreadable-basic.js
@@ -0,0 +1,37 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/ */
+"use strict";
+
+const x = Object.freeze([1, 2, 3]);
+
+let fakeArray = {
+    [Symbol.isConcatSpreadable]: true,
+    length: 2,
+    0: "hello",
+    1: "world"
+}
+assertDeepEq(x.concat(fakeArray), [1, 2, 3, "hello", "world"]);
+assertDeepEq(x.concat(fakeArray, fakeArray), [1, 2, 3, "hello", "world", "hello", "world"]);
+
+for (let truthy of [true, 3.41, "abc", Symbol(), {}]) {
+    let obj = {[Symbol.isConcatSpreadable]: truthy, length: 1, 0: "hey"}
+    assertDeepEq(x.concat(obj), [1, 2, 3, "hey"]);
+}
+
+for (let notTruthy of [null, undefined, false, 0, NaN, ""]) {
+    let obj = {[Symbol.isConcatSpreadable]: notTruthy, length: 1, 0: "hey"}
+    assertDeepEq(x.concat(obj), [1, 2, 3, obj]);
+}
+
+let array = [5, 4];
+assertDeepEq(x.concat(array), [1, 2, 3, 5, 4]);
+
+// Can make arrays non-spreadable
+array[Symbol.isConcatSpreadable] = false;
+assertDeepEq(x.concat(array), [1, 2, 3, [5, 4]]);
+
+// Explicitly spreadable
+array[Symbol.isConcatSpreadable] = true;
+assertDeepEq(x.concat(array), [1, 2, 3, 5, 4]);
+
+reportCompare(true, true);