Merge pull request #2640 from shvaikalesh/async-yield-return-is-awaited

Test that yield* return() awaits received value

test/language/statements/async-generator/yield-star-return-missing-value-is-awaited.js

@@ -0,0 +1,44 @@
+// 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's "return" method is missing,
+  received value is awaited before forwarded to the runtime.
+info: |
+  YieldExpression : yield * AssignmentExpression
+
+  [...]
+  7. Repeat,
+    [...]
+    c. Else,
+      i. Assert: received.[[Type]] is return.
+      ii. Let return be ? GetMethod(iterator, "return").
+      iii. If return is undefined, then
+        1. If generatorKind is async, then set received.[[Value]] to ? Await(received.[[Value]]).
+        2. Return Completion(received).
+features: [Symbol.asyncIterator, async-iteration]
+flags: [async]
+---*/
+
+var asyncIterable = {
+  [Symbol.asyncIterator]: function() {
+    return this;
+  },
+  next: function() {
+    return {value: 1, done: false};
+  },
+};
+
+async function* asyncGenerator() {
+  yield* asyncIterable;
+}
+
+var asyncIterator = asyncGenerator();
+asyncIterator.next().then(function() {
+  var promise = Promise.resolve(2).then(() => 3);
+  return asyncIterator.return(promise).then(function(result) {
+    assert.sameValue(result.value, 3);
+    assert.sameValue(result.done, true);
+  });
+}).then($DONE, $DONE);