Add test case for tc39/ecma262#1172

test/language/statements/async-generator/yield-star-async-from-sync-iterator-inaccessible.js

@@ -0,0 +1,55 @@
+// Copyright (C) 2019 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-createasyncfromsynciterator
+description: >
+  Async-from-Sync Iterator instances are not accessible from user code.
+info: |
+  25.1.4.1 CreateAsyncFromSyncIterator ( syncIteratorRecord )
+    1. Let asyncIterator be ! ObjectCreate(%AsyncFromSyncIteratorPrototype%, « [[SyncIteratorRecord]] »).
+    2. Set asyncIterator.[[SyncIteratorRecord]] to syncIteratorRecord.
+    3. Let nextMethod be ! Get(asyncIterator, "next").
+    4. Let iteratorRecord be Record { [[Iterator]]: asyncIterator, [[NextMethod]]: nextMethod, [[Done]]: false }.
+    5. Return iteratorRecord.
+
+  14.4.14 Runtime Semantics: Evaluation
+    YieldExpression : yield * AssignmentExpression
+      1. Let generatorKind be ! GetGeneratorKind().
+      ...
+      4. Let iteratorRecord be ? GetIterator(value, generatorKind).
+      ...
+
+  7.4.1 GetIterator ( obj [ , hint [ , method ] ] )
+    ...
+    3. If method is not present, then
+      a. If hint is async, then
+        i. Set method to ? GetMethod(obj, @@asyncIterator).
+        ii. If method is undefined, then
+          1. Let syncMethod be ? GetMethod(obj, @@iterator).
+          2. Let syncIteratorRecord be ? GetIterator(obj, sync, syncMethod).
+          3. Return ? CreateAsyncFromSyncIterator(syncIteratorRecord).
+      ...
+
+flags: [async]
+features: [async-iteration]
+---*/
+
+var AsyncIteratorPrototype = Object.getPrototypeOf(async function*(){}.constructor.prototype.prototype);
+
+Object.defineProperty(AsyncIteratorPrototype, Symbol.iterator, {
+  get() {
+    throw new Error("@@iterator accessed");
+  }
+});
+
+Object.defineProperty(AsyncIteratorPrototype, Symbol.asyncIterator, {
+  get() {
+    throw new Error("@@asyncIterator accessed");
+  }
+});
+
+async function* g() {
+    yield* [];
+}
+g().next().then(() => $DONE(), $DONE);