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      1 // Copyright 2016 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 // Make sure it's an error if @@hasInstance isn't a function.
      6 (function() {
      7   var F = {};
      8   F[Symbol.hasInstance] = null;
      9   assertThrows(function() { 0 instanceof F; }, TypeError);
     10 })();
     11 
     12 // Make sure the result is coerced to boolean.
     13 (function() {
     14   var F = {};
     15   F[Symbol.hasInstance] = function() { return undefined; };
     16   assertEquals(0 instanceof F, false);
     17   F[Symbol.hasInstance] = function() { return null; };
     18   assertEquals(0 instanceof F, false);
     19   F[Symbol.hasInstance] = function() { return true; };
     20   assertEquals(0 instanceof F, true);
     21 })();
     22 
     23 // Make sure if @@hasInstance throws, we catch it.
     24 (function() {
     25   var F = {};
     26   F[Symbol.hasInstance] = function() { throw new Error("always throws"); }
     27   try {
     28     0 instanceof F;
     29   } catch (e) {
     30     assertEquals(e.message, "always throws");
     31   }
     32 })();
     33 
     34 // @@hasInstance works for bound functions.
     35 (function() {
     36   var BC = function() {};
     37   var bc = new BC();
     38   var bound = BC.bind();
     39   assertEquals(bound[Symbol.hasInstance](bc), true);
     40   assertEquals(bound[Symbol.hasInstance]([]), false);
     41 })();
     42 
     43 // if OrdinaryHasInstance is passed a non-callable receiver, return false.
     44 assertEquals(Function.prototype[Symbol.hasInstance].call(Array, []), true);
     45 assertEquals(Function.prototype[Symbol.hasInstance].call({}, {}), false);
     46 
     47 // OrdinaryHasInstance passed a non-object argument returns false.
     48 assertEquals(Function.prototype[Symbol.hasInstance].call(Array, 0), false);
     49 
     50 // Cannot assign to @@hasInstance with %FunctionPrototype%.
     51 (function() {
     52   "use strict";
     53   function F() {}
     54   assertThrows(function() { F[Symbol.hasInstance] = (v) => v }, TypeError);
     55 })();
     56 
     57 // Check correct invocation of @@hasInstance handler on function instance.
     58 (function() {
     59   function F() {}
     60   var counter = 0;
     61   var proto = Object.getPrototypeOf(F);
     62   Object.setPrototypeOf(F, null);
     63   F[Symbol.hasInstance] = function(v) { ++counter; return true };
     64   Object.setPrototypeOf(F, proto);
     65   assertTrue(1 instanceof F);
     66   assertEquals(1, counter);
     67 })();
     68