1 files changed, 36 insertions, 0 deletions
diff --git a/js/src/tests/non262/TypedArray/from_constructor.js b/js/src/tests/non262/TypedArray/from_constructor.js
new file mode 100644
index 0000000000..0b0773b85c
--- /dev/null
+++ b/js/src/tests/non262/TypedArray/from_constructor.js
@@ -0,0 +1,36 @@
+for (var constructor of anyTypedArrayConstructors) {
+    // Note %TypedArray%.from(iterable) calls 'this' with an argument whose value is
+    // `[...iterable].length`, while Array.from(iterable) doesn't pass any argument.
+    constructor.from.call(function(len){
+        assertEq(len, 3);
+        return new constructor(len);
+    }, Array(3));
+
+    // If the 'this' value passed to %TypedArray.from is not a constructor,
+    // then an exception is thrown, while Array.from will use Array as it's constructor.
+    var arr = [3, 4, 5];
+    var nonconstructors = [
+        {}, Math, Object.getPrototypeOf, undefined, 17,
+        () => ({})  // arrow functions are not constructors
+    ];
+    for (var v of nonconstructors) {
+        assertThrowsInstanceOf(() => {
+            constructor.from.call(v, arr);
+        }, TypeError);
+    }
+
+    // %TypedArray%.from does not get confused if global constructors for typed arrays
+    // are replaced with another constructor.
+    function NotArray(...rest) {
+        return new constructor(...rest);
+    }
+    var RealArray = constructor;
+    NotArray.from = constructor.from;
+    this[constructor.name] = NotArray;
+    assertEq(RealArray.from([1]) instanceof RealArray, true);
+    assertEq(NotArray.from([1]) instanceof RealArray, true);
+    this[constructor.name] = RealArray;
+}
+
+if (typeof reportCompare === "function")
+    reportCompare(true, true);