1 files changed, 56 insertions, 0 deletions
diff --git a/js/src/tests/non262/Array/from_constructor.js b/js/src/tests/non262/Array/from_constructor.js
new file mode 100644
index 0000000000..6846ef09aa
--- /dev/null
+++ b/js/src/tests/non262/Array/from_constructor.js
@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/ */
+
+// Array.from can be applied to any constructor.
+// For example, the Date builtin constructor.
+var d = Array.from.call(Date, ["A", "B"]);
+assertEq(Array.isArray(d), false);
+assertEq(Object.prototype.toString.call(d), "[object Date]");
+assertEq(Object.getPrototypeOf(d), Date.prototype);
+assertEq(d.length, 2);
+assertEq(d[0], "A");
+assertEq(d[1], "B");
+
+// Or Object.
+var obj = Array.from.call(Object, []);
+assertEq(Array.isArray(obj), false);
+assertEq(Object.getPrototypeOf(obj), Object.prototype);
+assertEq(Object.getOwnPropertyNames(obj).join(","), "length");
+assertEq(obj.length, 0);
+
+// Or any JS function.
+function C(arg) {
+    this.args = arguments;
+}
+var c = Array.from.call(C, {length: 1, 0: "zero"});
+assertEq(c instanceof C, true);
+assertEq(c.args.length, 1);
+assertEq(c.args[0], 1);
+assertEq(c.length, 1);
+assertEq(c[0], "zero");
+
+// If the 'this' value passed to Array.from is not a constructor,
+// a plain Array is created.
+var arr = [3, 4, 5];
+var nonconstructors = [
+    {}, Math, Object.getPrototypeOf, undefined, 17,
+    () => ({})  // arrow functions are not constructors
+];
+for (var v of nonconstructors) {
+    obj = Array.from.call(v, arr);
+    assertEq(Array.isArray(obj), true);
+    assertDeepEq(obj, arr);
+}
+
+// Array.from does not get confused if global.Array is replaced with another
+// constructor.
+function NotArray() {
+}
+var RealArray = Array;
+NotArray.from = Array.from;
+Array = NotArray;
+assertEq(RealArray.from([1]) instanceof RealArray, true);
+assertEq(NotArray.from([1]) instanceof NotArray, true);
+
+if (typeof reportCompare === 'function')
+    reportCompare(0, 0);