array-empty-iter-close-null.js (2017B)
1 // This file was procedurally generated from the following sources: 2 // - src/dstr-assignment/array-empty-iter-close-null.case 3 // - src/dstr-assignment/error/for-of.template 4 /*--- 5 description: IteratorClose throws a TypeError when `return` returns a non-Object value (For..of statement) 6 esid: sec-for-in-and-for-of-statements-runtime-semantics-labelledevaluation 7 features: [Symbol.iterator, destructuring-binding] 8 flags: [generated] 9 info: | 10 IterationStatement : 11 for ( LeftHandSideExpression of AssignmentExpression ) Statement 12 13 1. Let keyResult be the result of performing ? ForIn/OfHeadEvaluation(« », 14 AssignmentExpression, iterate). 15 2. Return ? ForIn/OfBodyEvaluation(LeftHandSideExpression, Statement, 16 keyResult, assignment, labelSet). 17 18 13.7.5.13 Runtime Semantics: ForIn/OfBodyEvaluation 19 20 [...] 21 4. If destructuring is true and if lhsKind is assignment, then 22 a. Assert: lhs is a LeftHandSideExpression. 23 b. Let assignmentPattern be the parse of the source text corresponding to 24 lhs using AssignmentPattern as the goal symbol. 25 [...] 26 27 ArrayAssignmentPattern : [ ] 28 29 1. Let iterator be GetIterator(value). 30 2. ReturnIfAbrupt(iterator). 31 3. Return IteratorClose(iterator, NormalCompletion(empty)). 32 33 7.4.6 IteratorClose( iterator, completion ) 34 35 [...] 36 6. Let innerResult be Call(return, iterator, « »). 37 7. If completion.[[type]] is throw, return Completion(completion). 38 8. If innerResult.[[type]] is throw, return Completion(innerResult). 39 9. If Type(innerResult.[[value]]) is not Object, throw a TypeError 40 exception. 41 42 ---*/ 43 var iterable = {}; 44 var iterator = { 45 next: function() { 46 return { done: true }; 47 }, 48 return: function() { 49 return null; 50 } 51 }; 52 iterable[Symbol.iterator] = function() { 53 return iterator; 54 }; 55 56 var counter = 0; 57 58 assert.throws(TypeError, function() { 59 for ([] of [iterable]) { 60 counter += 1; 61 } 62 counter += 1; 63 }); 64 65 assert.sameValue(counter, 0); 66 67 reportCompare(0, 0);