tor-browser

The Tor Browser
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star-rhs-iter-thrw-violation-no-rtrn.js (2451B)

      1 // Copyright (C) 2016 the V8 project authors. All rights reserved.
      2 // This code is governed by the BSD license found in the LICENSE file.
      3 /*---
      4 esid: sec-generator-function-definitions-runtime-semantics-evaluation
      5 es6id: 14.4.14
      6 description: >
      7  Abrupt completion returned after protocol violation (and a `return` method
      8  is not defined)
      9 info: |
     10  YieldExpression : yield * AssignmentExpression
     11 
     12  1. Let exprRef be the result of evaluating AssignmentExpression.
     13  2. Let value be ? GetValue(exprRef).
     14  3. Let iterator be ? GetIterator(value).
     15  4. Let received be NormalCompletion(undefined).
     16  5. Repeat
     17     a. If received.[[Type]] is normal, then
     18        [...]
     19     b. Else if received.[[Type]] is throw, then
     20        i. Let throw be ? GetMethod(iterator, "throw").
     21        ii. If throw is not undefined, then
     22            [...]
     23        iii. Else,
     24             1. NOTE: If iterator does not have a throw method, this throw is
     25                going to terminate the yield* loop. But first we need to give
     26                iterator a chance to clean up.
     27             2. Perform ? IteratorClose(iterator, Completion{[[Type]]: normal,
     28                [[Value]]: empty, [[Target]]: empty}).
     29             3. NOTE: The next step throws a TypeError to indicate that there
     30                was a yield* protocol violation: iterator does not have a throw
     31                method.
     32             4. Throw a TypeError exception.
     33 
     34  7.4.6 IteratorClose
     35 
     36  1. Assert: Type(iterator) is Object.
     37  2. Assert: completion is a Completion Record.
     38  3. Let return be ? GetMethod(iterator, "return").
     39  4. If return is undefined, return Completion(completion).
     40 features: [generators, Symbol.iterator]
     41 ---*/
     42 
     43 var badIter = {};
     44 var throwCount = 0;
     45 var returnCount = 0;
     46 var spyResult = {
     47  next: function() {
     48    return { done: false };
     49  }
     50 };
     51 Object.defineProperty(spyResult, 'throw', {
     52  get: function() {
     53    throwCount += 1;
     54  }
     55 });
     56 Object.defineProperty(spyResult, 'return', {
     57  get: function() {
     58    returnCount += 1;
     59  }
     60 });
     61 badIter[Symbol.iterator] = function() {
     62  return spyResult;
     63 };
     64 function* g() {
     65  try {
     66    yield * badIter;
     67  } catch (err) {
     68    caught = err;
     69  }
     70 }
     71 var iter = g();
     72 var caught;
     73 
     74 iter.next();
     75 iter.throw();
     76 
     77 assert.sameValue(throwCount, 1, '`throw` property access');
     78 assert.sameValue(returnCount, 1, '`return` property access');
     79 assert.sameValue(typeof caught, 'object');
     80 assert.sameValue(caught.constructor, TypeError);
     81 
     82 reportCompare(0, 0);