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+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-generator-function-definitions-runtime-semantics-evaluation
+description: >
+ If <iterator>.throw is an object emulating `undefined` (e.g. `document.all`
+ in browsers), it shouldn't be treated as if it were actually `undefined` by
+ the yield* operator.
+info: |
+ YieldExpression : yield * AssignmentExpression
+
+ [...]
+ 7. Repeat,
+ [...]
+ b. Else if received.[[Type]] is throw, then
+ i. Let throw be ? GetMethod(iterator, "throw").
+ ii. If throw is not undefined, then
+ 1. Let innerResult be ? Call(throw, iterator, « received.[[Value]] »).
+ [...]
+ 4. If Type(innerResult) is not Object, throw a TypeError exception.
+features: [generators, IsHTMLDDA]
+---*/
+
+var IsHTMLDDA = $262.IsHTMLDDA;
+var returnCalls = 0;
+var inner = {
+ [Symbol.iterator]() { return this; },
+ next() { return {done: false}; },
+ throw: IsHTMLDDA,
+ return() {
+ returnCalls += 1;
+ return {done: true};
+ },
+};
+
+var outer = (function* () { yield* inner; })();
+outer.next();
+
+assert.throws(TypeError, function() {
+ // `IsHTMLDDA` is called here with `iter` as `this` and `emptyString` as the
+ // sole argument, and it's specified to return `null` under these conditions.
+ // As `iter`'s iteration isn't ending because of a throw, the iteration
+ // protocol will then throw a `TypeError` because `null` isn't an object.
+ var emptyString = "";
+ outer.throw(emptyString);
+});
+
+assert.sameValue(returnCalls, 0);
+
+reportCompare(0, 0);