ES6: Desugaring of instanceof to support @@hasInstance

test/mjsunit/harmony/instanceof-es6.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-instanceof
+
+// Make sure it's an error if @@hasInstance isn't a function.
+(function() {
+  var F = {};
+  F[Symbol.hasInstance] = null;
+  assertThrows(function() { 0 instanceof F; }, TypeError);
+})();
+
+// Make sure the result is coerced to boolean.
+(function() {
+  var F = {};
+  F[Symbol.hasInstance] = function() { return undefined; };
+  assertEquals(0 instanceof F, false);
+  F[Symbol.hasInstance] = function() { return null; };
+  assertEquals(0 instanceof F, false);
+  F[Symbol.hasInstance] = function() { return true; };
+  assertEquals(0 instanceof F, true);
+})();
+
+// Make sure if @@hasInstance throws, we catch it.
+(function() {
+  var F = {};
+  F[Symbol.hasInstance] = function() { throw new Error("always throws"); }
+  try {
+    0 instanceof F;
+  } catch (e) {
+    assertEquals(e.message, "always throws");
+  }
+})();
+
+// @@hasInstance works for bound functions.
+(function() {
+  var BC = function() {};
+  var bc = new BC();
+  var bound = BC.bind();
+  assertEquals(bound[Symbol.hasInstance](bc), true);
+  assertEquals(bound[Symbol.hasInstance]([]), false);
+})();
+
+// if OrdinaryHasInstance is passed a non-callable receiver, return false.
+assertEquals(Function.prototype[Symbol.hasInstance].call(Array, []), true);
+assertEquals(Function.prototype[Symbol.hasInstance].call({}, {}), false);
+
+// OrdinaryHasInstance passed a non-object argument returns false.
+assertEquals(Function.prototype[Symbol.hasInstance].call(Array, 0), false);