async-iteration: AsyncGeneratorPrototype tests (#1451)

test/built-ins/AsyncGeneratorPrototype/Symbol.toStringTag.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-tostringtag
+description: >
+    `Symbol.toStringTag` property descriptor
+info: |
+    The initial value of the @@toStringTag property is the String value
+    "AsyncGenerator".
+
+    This property has the attributes { [[Writable]]: false, [[Enumerable]]:
+    false, [[Configurable]]: true }.
+
+includes: [propertyHelper.js]
+features: [async-iteration, Symbol.toStringTag]
+---*/
+
+var AsyncGeneratorPrototype = Object.getPrototypeOf(
+  Object.getPrototypeOf(async function*() {}())
+);
+
+verifyProperty(AsyncGeneratorPrototype, Symbol.toStringTag, {
+  value: 'AsyncGenerator',
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});

test/built-ins/AsyncGeneratorPrototype/constructor.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-constructor
+description: >
+    The GeneratorPrototype intrinsic's constructor.
+info: |
+    AsyncGenerator.prototype.constructor
+
+    The initial value of AsyncGenerator.prototype.constructor is the
+    intrinsic object %AsyncGenerator%.
+
+    This property has the attributes { [[Writable]]: false,
+    [[Enumerable]]: false, [[Configurable]]: true }.
+
+includes: [propertyHelper.js]
+features: [async-iteration]
+---*/
+
+async function* g() {}
+var AsyncGenerator = Object.getPrototypeOf(g);
+var AsyncGeneratorPrototype = AsyncGenerator.prototype;
+
+verifyProperty(AsyncGeneratorPrototype, 'constructor', {
+  value: AsyncGenerator,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});

test/built-ins/AsyncGeneratorPrototype/next/iterator-result-prototype.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-next
+description: >
+  "next" returns a promise for an IteratorResult object
+info: |
+  AsyncGenerator.prototype.next ( value )
+  1. Let generator be the this value.
+  2. Let completion be NormalCompletion(value).
+  3. Return ! AsyncGeneratorEnqueue(generator, completion).
+
+  AsyncGeneratorEnqueue ( generator, completion )
+  ...
+  4. Let queue be generator.[[AsyncGeneratorQueue]].
+  5. Let request be AsyncGeneratorRequest{[[Completion]]: completion,
+     [[Capability]]: promiseCapability}.
+  6. Append request to the end of queue.
+  ...
+
+  AsyncGeneratorResolve ( generator, value, done )
+  1. Assert: generator is an AsyncGenerator instance.
+  2. Let queue be generator.[[AsyncGeneratorQueue]].
+  3. Assert: queue is not an empty List.
+  4. Remove the first element from queue and let next be the value of that element.
+  5. Let promiseCapability be next.[[Capability]].
+  6. Let iteratorResult be ! CreateIterResultObject(value, done).
+  7. Perform ! Call(promiseCapability.[[Resolve]], undefined, « iteratorResult »).
+  ...
+
+flags: [async]
+features: [async-iteration]
+---*/
+
+async function* g() {}
+
+g().next().then(function (result) {
+  assert(
+    Object.hasOwnProperty.call(result, 'value'), 'Has "own" property `value`'
+  );
+  assert(
+    Object.hasOwnProperty.call(result, 'done'), 'Has "own" property `done`'
+  );
+  assert.sameValue(Object.getPrototypeOf(result), Object.prototype);
+}).then($DONE, $DONE)

test/built-ins/AsyncGeneratorPrototype/next/length.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-next
+description: >
+  AsyncGenerator.prototype.next.length is 1.
+info: |
+  AsyncGenerator.prototype.next ( value )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [async-iteration]
+---*/
+
+async function* g() {}
+var AsyncGeneratorPrototype = Object.getPrototypeOf(g).prototype;
+
+verifyProperty(AsyncGeneratorPrototype.next, "length", {
+  value: 1,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+

test/built-ins/AsyncGeneratorPrototype/next/name.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-next
+description: >
+  Generator.prototype.next.name is "next".
+info: |
+  Generator.prototype.next ( value )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, that is not
+    identified as an anonymous function has a name property whose value
+    is a String.
+
+    Unless otherwise specified, the name property of a built-in Function
+    object, if it exists, has the attributes { [[Writable]]: false,
+    [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [generators]
+---*/
+
+async function* g() {}
+var AsyncGeneratorPrototype = Object.getPrototypeOf(g).prototype;
+
+verifyProperty(AsyncGeneratorPrototype.next, "name", {
+  value: "next",
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});

test/built-ins/AsyncGeneratorPrototype/next/prop-desc.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-next
+description: GeneratorPrototype.next property description
+info: |
+  This property has the attributes { [[Writable]]: false, [[Enumerable]]:
+  false, [[Configurable]]: false }.
+includes: [propertyHelper.js]
+features: [async-iteration]
+---*/
+
+async function* g() {}
+var AsyncGeneratorPrototype = Object.getPrototypeOf(g).prototype;
+
+verifyProperty(AsyncGeneratorPrototype, "next", {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});

test/built-ins/AsyncGeneratorPrototype/next/request-queue-await-order.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-next
+description: next() requests from iterator processed in order, await
+info: >
+  AsyncGenerator.prototype.next ( value )
+  1. Let generator be the this value.
+  2. Let completion be NormalCompletion(value).
+  3. Return ! AsyncGeneratorEnqueue(generator, completion).
+
+  AsyncGeneratorEnqueue ( generator, completion )
+  ...
+  4. Let queue be generator.[[AsyncGeneratorQueue]].
+  5. Let request be AsyncGeneratorRequest{[[Completion]]: completion,
+     [[Capability]]: promiseCapability}.
+  6. Append request to the end of queue.
+  ...
+
+  AsyncGeneratorResolve ( generator, value, done )
+  ...
+  2. Let queue be generator.[[AsyncGeneratorQueue]].
+  3. Assert: queue is not an empty List.
+  4. Remove the first element from queue and let next be the value of that element.
+  ...
+
+flags: [async]
+features: [async-iteration]
+---*/
+
+var yieldorder = 0;
+var resolveLatePromise;
+
+function resolveLater() {
+  return new Promise(resolve => {
+    resolveLatePromise = resolve;
+  });
+}
+
+async function* g() {
+  yield resolveLater();
+  yield ++yieldorder;
+}
+
+var iter = g();
+
+assert.sameValue(yieldorder, 0);
+
+var item1 = iter.next();
+var item2 = iter.next();
+var item3 = iter.next();
+
+async function awaitnexts() {
+  assert.sameValue((await item3).value, undefined)
+  assert.sameValue(yieldorder, 2, "All next requests have been proccessed.")
+  assert.sameValue((await item2).value, 2)
+  assert.sameValue((await item1).value, 1)
+}
+
+awaitnexts().then($DONE, $DONE);
+
+// At this point:
+//   yieldorder == 0
+//   item1 is an unresolved promise
+resolveLatePromise(++yieldorder);

test/built-ins/AsyncGeneratorPrototype/next/request-queue-order-state-executing.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-asyncgenerator-prototype-throw
+description: next() call while iterator is in state executing
+info: |
+  AsyncGenerator.prototype.next ( value )
+  1. Let generator be the this value.
+  2. Let completion be NormalCompletion(value).
+  3. Return ! AsyncGeneratorEnqueue(generator, completion).
+
+  AsyncGeneratorEnqueue ( generator, completion )
+  ...
+  4. Let queue be generator.[[AsyncGeneratorQueue]].
+  5. Let request be AsyncGeneratorRequest{[[Completion]]: completion,
+     [[Capability]]: promiseCapability}.
+  6. Append request to the end of queue.
+  ...
+
+  AsyncGeneratorResolve ( generator, value, done )
+  ...
+  2. Let queue be generator.[[AsyncGeneratorQueue]].
+  3. Assert: queue is not an empty List.
+  4. Remove the first element from queue and let next be the value of that element.
+  ...
+
+flags: [async]
+features: [async-iteration]
+---*/
+
+var iter, result;
+var executionorder = 0;
+var valueisset = false;
+
+async function* g() {
+
+  iter.next().then(
+    function(result) {
+      assert(valueisset, "variable valueisset should be set to true");
+      assert.sameValue(++executionorder, 2);
+      assert.sameValue(result.value, 2);
+      assert.sameValue(result.done, false);
+    },
+    function() {
+      $DONE(new Test262Error("next() should result in resolved promise."));
+    }
+  ).catch($DONE)
+
+  valueisset = true;
+
+  yield 1;
+  yield 2;
+}
+
+iter = g();
+
+iter.next().then(function(result) {
+  assert.sameValue(++executionorder, 1);
+  assert.sameValue(result.value, 1);
+  assert.sameValue(result.done, false);
+
+  iter.next().then(function(result) {
+    assert.sameValue(++executionorder, 3);
+    assert.sameValue(result.value, undefined);
+    assert.sameValue(result.done, true);
+  }).then($DONE, $DONE);
+
+}).catch($DONE);
+
+
+

test/built-ins/AsyncGeneratorPrototype/next/request-queue-order.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-next
+description: queue
+info: >
+  AsyncGenerator.prototype.next ( value )
+  1. Let generator be the this value.
+  2. Let completion be NormalCompletion(value).
+  3. Return ! AsyncGeneratorEnqueue(generator, completion).
+
+  AsyncGeneratorEnqueue ( generator, completion )
+  ...
+  4. Let queue be generator.[[AsyncGeneratorQueue]].
+  5. Let request be AsyncGeneratorRequest{[[Completion]]: completion,
+     [[Capability]]: promiseCapability}.
+  6. Append request to the end of queue.
+  ...
+
+  AsyncGeneratorResolve ( generator, value, done )
+  ...
+  2. Let queue be generator.[[AsyncGeneratorQueue]].
+  3. Assert: queue is not an empty List.
+  4. Remove the first element from queue and let next be the value of that element.
+  ...
+
+flags: [async]
+features: [async-iteration]
+---*/
+
+var order = 0;
+
+async function* g() {
+  yield 'first';
+  yield 'second';
+}
+
+var iter = g();
+
+var item1 = iter.next();
+var item2 = iter.next();
+var item3 = iter.next();
+
+var resolvedorder = 0;
+
+Promise.all([
+
+  item3.then(function(result) {
+    resolvedorder++;
+    assert.sameValue(resolvedorder, 3);
+    assert.sameValue(result.value, undefined);
+    assert.sameValue(result.done, true);
+  }),
+
+  item2.then(function(result) {
+    resolvedorder++;
+    assert.sameValue(resolvedorder, 2);
+    assert.sameValue(result.value, "second");
+    assert.sameValue(result.done, false);
+  }),
+
+  item1.then(function(result) {
+    resolvedorder++;
+    assert.sameValue(resolvedorder, 1);
+    assert.sameValue(result.value, "first");
+    assert.sameValue(result.done, false);
+  })
+
+]).then(function() { $DONE(); }, $DONE);
+

test/built-ins/AsyncGeneratorPrototype/next/request-queue-promise-resolve-order.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-next
+description: next() requests from iterator processed in order, then
+info: >
+  AsyncGenerator.prototype.next ( value )
+  1. Let generator be the this value.
+  2. Let completion be NormalCompletion(value).
+  3. Return ! AsyncGeneratorEnqueue(generator, completion).
+
+  AsyncGeneratorEnqueue ( generator, completion )
+  ...
+  4. Let queue be generator.[[AsyncGeneratorQueue]].
+  5. Let request be AsyncGeneratorRequest{[[Completion]]: completion,
+     [[Capability]]: promiseCapability}.
+  6. Append request to the end of queue.
+  ...
+
+  AsyncGeneratorResolve ( generator, value, done )
+  ...
+  2. Let queue be generator.[[AsyncGeneratorQueue]].
+  3. Assert: queue is not an empty List.
+  4. Remove the first element from queue and let next be the value of that element.
+  ...
+
+flags: [async]
+features: [async-iteration]
+---*/
+
+var yieldorder = 0;
+var resolveLatePromise;
+
+function resolveLater() {
+  return new Promise(resolve => {
+    resolveLatePromise = resolve;
+  });
+}
+
+async function* g() {
+  yield resolveLater();
+  yield ++yieldorder;
+}
+
+var iter = g();
+
+var item1 = iter.next();
+var item2 = iter.next();
+var item3 = iter.next();
+
+var resolvedorder = 0;
+
+Promise.all([
+
+  item3.then(function(result) {
+    resolvedorder++;
+    assert.sameValue(resolvedorder, 3);
+    assert.sameValue(result.value, undefined);
+    assert.sameValue(result.done, true);
+  }),
+
+  item2.then(function(result) {
+    resolvedorder++;
+    assert.sameValue(resolvedorder, 2);
+    assert.sameValue(result.value, 2);
+    assert.sameValue(result.done, false);
+  }),
+
+  item1.then(function(result) {
+    resolvedorder++;
+    assert.sameValue(resolvedorder, 1);
+    assert.sameValue(result.value, 1);
+    assert.sameValue(result.done, false);
+  })
+
+]).then(function() { $DONE(); }, $DONE);
+
+// At this point:
+//   yieldorder == 0
+//   item1 is an unresolved promise
+resolveLatePromise(++yieldorder);

test/built-ins/AsyncGeneratorPrototype/next/return-promise.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-next
+description: >
+  "next" returns a promise for an IteratorResult object
+info: |
+  AsyncGenerator.prototype.next ( value )
+  1. Let generator be the this value.
+  2. Let completion be NormalCompletion(value).
+  3. Return ! AsyncGeneratorEnqueue(generator, completion).
+
+  AsyncGeneratorEnqueue ( generator, completion )
+  ...
+  2. Let promiseCapability be ! NewPromiseCapability(%Promise%).
+  ...
+  9. Return promiseCapability.[[Promise]].
+
+features: [async-iteration]
+---*/
+
+async function* g() {}
+var result = g().next()
+
+assert(result instanceof Promise)

test/built-ins/AsyncGeneratorPrototype/next/this-val-not-async-generator.js

+// Copyright 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-asyncgenerator-prototype-next
+description: next rejects promise when `this` value is not an async generator
+info: |
+  AsyncGenerator.prototype.next ( value )
+  1. Let generator be the this value.
+  2. Let completion be NormalCompletion(value).
+  3. Return ! AsyncGeneratorEnqueue(generator, completion).
+
+  AsyncGeneratorEnqueue ( generator, completion )
+  ...
+  3. If Type(generator) is not Object, or if generator does not have an
+     [[AsyncGeneratorState]] internal slot, then
+    a. Let badGeneratorError be a newly created TypeError object.
+    b. Perform ! Call(promiseCapability.[[Reject]], undefined, « badGeneratorError »).
+    c. Return promiseCapability.[[Promise]].
+
+flags: [async]
+features: [async-iteration]
+---*/
+
+async function* g() {}
+var AsyncGeneratorPrototype = Object.getPrototypeOf(g).prototype;
+
+function* syncGenerator() {}
+var syncIterator = syncGenerator()
+
+var testPromises = [
+  AsyncGeneratorPrototype.next.call({}).then(
+    function () {
+      throw new Test262Error("AsyncGeneratorPrototype.next should reject promise" +
+                             " when `this` value is an object");
+    },
+    function (e) {
+      if (!(e instanceof TypeError)) {
+       throw new Test262Error("(object) expected TypeError but got " + e);
+      }
+    }
+  ),
+  AsyncGeneratorPrototype.next.call(function() {}).then(
+    function () {
+      throw new Test262Error("AsyncGeneratorPrototype.next should reject promise" +
+                             " when `this` value is a function");
+    },
+    function (e) {
+      if (!(e instanceof TypeError)) {
+       throw new Test262Error("(function) expected TypeError but got " + e);
+      }
+    }
+  ),
+  AsyncGeneratorPrototype.next.call(g).then(
+    function () {
+      throw new Test262Error("AsyncGeneratorPrototype.next should reject promise" +
+                             " when `this` value is an async generator function");
+    },
+    function (e) {
+      if (!(e instanceof TypeError)) {
+       throw new Test262Error("(async generator function) expected TypeError but got " + e);
+      }
+    }
+  ),
+  AsyncGeneratorPrototype.next.call(g.prototype).then(
+    function () {
+      throw new Test262Error("AsyncGeneratorPrototype.next should reject promise" +
+                             " when `this` value is an async generator function prototype object");
+    },
+    function (e) {
+      if (!(e instanceof TypeError)) {
+       throw new Test262Error("(async generator function prototype) expected TypeError but got " + e);
+      }
+    },
+  ),
+  AsyncGeneratorPrototype.next.call(syncIterator).then(
+    function () {
+      throw new Test262Error("AsyncGeneratorPrototype.next should reject promise" +
+                             " when `this` value is a generator");
+    },
+    function (e) {
+      if (!(e instanceof TypeError)) {
+       throw new Test262Error("(generator) expected TypeError but got " + e);
+      }
+    }
+  )
+]
+
+Promise.all(testPromises).then(() => {}).then($DONE, $DONE)

test/built-ins/AsyncGeneratorPrototype/next/this-val-not-object.js

+// Copyright 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-asyncgenerator-prototype-next
+description: next rejects promise when `this` value not an object
+info: |
+  AsyncGenerator.prototype.next ( value )
+  1. Let generator be the this value.
+  2. Let completion be NormalCompletion(value).
+  3. Return ! AsyncGeneratorEnqueue(generator, completion).
+
+  AsyncGeneratorEnqueue ( generator, completion )
+  ...
+  3. If Type(generator) is not Object, or if generator does not have an
+     [[AsyncGeneratorState]] internal slot, then
+    a. Let badGeneratorError be a newly created TypeError object.
+    b. Perform ! Call(promiseCapability.[[Reject]], undefined, « badGeneratorError »).
+    c. Return promiseCapability.[[Promise]].
+
+flags: [async]
+features: [async-iteration]
+---*/
+
+async function* g() {}
+var AsyncGeneratorPrototype = Object.getPrototypeOf(g).prototype;
+
+var symbol = Symbol();
+
+var testPromises = [
+  AsyncGeneratorPrototype.next.call(undefined).then(
+    function () {
+      throw new Test262Error("AsyncGeneratorPrototype.next should reject promise" +
+                             " when `this` value `undefined`");
+    },
+    function (e) {
+      if (!(e instanceof TypeError)) {
+       throw new Test262Error("(undefined) expected TypeError but got " + e);
+      }
+    }
+  ),
+  AsyncGeneratorPrototype.next.call(1).then(
+    function () {
+      throw new Test262Error("AsyncGeneratorPrototype.next should reject promise" +
+                             " when `this` value is a Number");
+    },
+    function (e) {
+      if (!(e instanceof TypeError)) {
+       throw new Test262Error("(Number) expected TypeError but got " + e);
+      }
+    }
+  ),
+  AsyncGeneratorPrototype.next.call("string").then(
+    function () {
+      throw new Test262Error("AsyncGeneratorPrototype.next should reject promise" +
+                             " when `this` value is a String");
+    },
+    function (e) {
+      if (!(e instanceof TypeError)) {
+       throw new Test262Error("(String) expected TypeError but got " + e);
+      }
+    }
+  ),
+  AsyncGeneratorPrototype.next.call(null).then(
+    function () {
+      throw new Test262Error("AsyncGeneratorPrototype.next should reject promise" +
+                             " when `this` value `null`");
+    },
+    function (e) {
+      if (!(e instanceof TypeError)) {
+       throw new Test262Error("(null) expected TypeError but got " + e);
+      }
+    }
+  ),
+  AsyncGeneratorPrototype.next.call(true).then(
+    function () {
+      throw new Test262Error("AsyncGeneratorPrototype.next should reject promise" +
+                             " when `this` value is a Boolean");
+    },
+    function (e) {
+      if (!(e instanceof TypeError)) {
+       throw new Test262Error("(Boolean) expected TypeError but got " + e);
+      }
+    }
+  ),
+  AsyncGeneratorPrototype.next.call(symbol).then(
+    function () {
+      throw new Test262Error("AsyncGeneratorPrototype.next should reject promise" +
+                             " when `this` value is a Symbol");
+    },
+    function (e) {
+      if (!(e instanceof TypeError)) {
+       throw new Test262Error("(Symbol) expected TypeError but got " + e);
+      }
+    }
+  )
+]
+
+Promise.all(testPromises).then(() => {}).then($DONE, $DONE)

test/built-ins/AsyncGeneratorPrototype/return/iterator-result-prototype.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-return
+description: >
+ "return" returns a promise for an IteratorResult object
+info: |
+  AsyncGenerator.prototype.return ( value )
+  1. Let generator be the this value.
+  2. Let completion be Completion{[[Type]]: return, [[Value]]: value,
+     [[Target]]: empty}.
+  3. Return ! AsyncGeneratorEnqueue(generator, completion).
+
+  AsyncGeneratorEnqueue ( generator, completion )
+  ...
+  4. Let queue be generator.[[AsyncGeneratorQueue]].
+  5. Let request be AsyncGeneratorRequest{[[Completion]]: completion,
+     [[Capability]]: promiseCapability}.
+  6. Append request to the end of queue.
+  ...
+
+  AsyncGeneratorResolve ( generator, value, done )
+  1. Assert: generator is an AsyncGenerator instance.
+  2. Let queue be generator.[[AsyncGeneratorQueue]].
+  3. Assert: queue is not an empty List.
+  4. Remove the first element from queue and let next be the value of that element.
+  5. Let promiseCapability be next.[[Capability]].
+  6. Let iteratorResult be ! CreateIterResultObject(value, done).
+  7. Perform ! Call(promiseCapability.[[Resolve]], undefined, « iteratorResult »).
+  ...
+
+flags: [async]
+features: [async-iteration]
+---*/
+
+async function* g() {}
+
+g().return().then(function (result) {
+  assert(
+    Object.hasOwnProperty.call(result, 'value'), 'Has "own" property `value`'
+  );
+  assert(
+    Object.hasOwnProperty.call(result, 'done'), 'Has "own" property `done`'
+  );
+  assert.sameValue(Object.getPrototypeOf(result), Object.prototype);
+}).then($DONE, $DONE)

test/built-ins/AsyncGeneratorPrototype/return/length.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-return
+description: >
+  AsyncGenerator.prototype.return.length is 1.
+info: |
+  AsyncGenerator.prototype.return ( value )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, has a length
+    property whose value is an integer. Unless otherwise specified, this
+    value is equal to the largest number of named arguments shown in the
+    subclause headings for the function description, including optional
+    parameters. However, rest parameters shown using the form “...name”
+    are not included in the default argument count.
+
+    Unless otherwise specified, the length property of a built-in Function
+    object has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+    [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [async-iteration]
+---*/
+
+async function* g() {}
+var AsyncGeneratorPrototype = Object.getPrototypeOf(g).prototype;
+
+verifyProperty(AsyncGeneratorPrototype.return, "length", {
+  value: 1,
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});
+

test/built-ins/AsyncGeneratorPrototype/return/name.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-return
+description: >
+  Generator.prototype.next.name is "return".
+info: |
+  Generator.prototype.return ( value )
+
+  17 ECMAScript Standard Built-in Objects:
+    Every built-in Function object, including constructors, that is not
+    identified as an anonymous function has a name property whose value
+    is a String.
+
+    Unless otherwise specified, the name property of a built-in Function
+    object, if it exists, has the attributes { [[Writable]]: false,
+    [[Enumerable]]: false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [generators]
+---*/
+
+async function* g() {}
+var AsyncGeneratorPrototype = Object.getPrototypeOf(g).prototype;
+
+verifyProperty(AsyncGeneratorPrototype.return, "name", {
+  value: "return",
+  enumerable: false,
+  writable: false,
+  configurable: true,
+});

test/built-ins/AsyncGeneratorPrototype/return/prop-desc.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-thow
+description: GeneratorPrototype.return property description
+info: |
+  This property has the attributes { [[Writable]]: false, [[Enumerable]]:
+  false, [[Configurable]]: false }.
+includes: [propertyHelper.js]
+features: [async-iteration]
+---*/
+
+async function* g() {}
+var AsyncGeneratorPrototype = Object.getPrototypeOf(g).prototype;
+
+verifyProperty(AsyncGeneratorPrototype, "return", {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});

test/built-ins/AsyncGeneratorPrototype/return/request-queue-order-state-executing.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-asyncgenerator-prototype-throw
+description: return() call while iterator is in state executing
+info: |
+  AsyncGenerator.prototype.return ( value )
+  1. Let generator be the this value.
+  2. Let completion be Completion{[[Type]]: return, [[Value]]: value, [[Target]]: empty}.
+  3. Return ! AsyncGeneratorEnqueue(generator, completion).
+
+  AsyncGeneratorEnqueue ( generator, completion )
+  ...
+  4. Let queue be generator.[[AsyncGeneratorQueue]].
+  5. Let request be AsyncGeneratorRequest{[[Completion]]: completion,
+     [[Capability]]: promiseCapability}.
+  6. Append request to the end of queue.
+  ...
+
+  AsyncGeneratorResolve ( generator, value, done )
+  ...
+  2. Let queue be generator.[[AsyncGeneratorQueue]].
+  3. Assert: queue is not an empty List.
+  4. Remove the first element from queue and let next be the value of that element.
+  ...
+
+flags: [async]
+features: [async-iteration]
+---*/
+
+var iter;
+var executionorder = 0;
+var valueisset = false;
+
+async function* g() {
+
+  iter.return(42).then(
+    function(result) {
+      assert(valueisset, "variable valueisset should be set to true");
+      assert.sameValue(++executionorder, 2);
+      assert.sameValue(result.value, 42);
+      assert.sameValue(result.done, true);
+    }
+  ).catch($DONE);
+
+  valueisset = true;
+
+  yield 1;
+  throw new Test262Error("This line should no be reached: generator closed by return");
+}
+
+iter = g();
+
+iter.next().then(function(result) {
+
+  assert.sameValue(++executionorder, 1);
+  assert.sameValue(result.value, 1);
+  assert.sameValue(result.done, false);
+
+  iter.next().then(function(result) {
+    assert.sameValue(++executionorder, 3);
+    assert.sameValue(result.value, undefined);
+    assert.sameValue(result.done, true);
+  }).then($DONE, $DONE);
+
+}).catch($DONE);

test/built-ins/AsyncGeneratorPrototype/return/return-promise.js

+// Copyright (C) 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-next
+description: >
+  "return" returns a promise
+info: |
+  AsyncGenerator.prototype.return ( value )
+  1. Let generator be the this value.
+  2. Let completion be Completion{[[Type]]: return, [[Value]]: value,
+     [[Target]]: empty}.
+  3. Return ! AsyncGeneratorEnqueue(generator, completion).
+
+  AsyncGeneratorEnqueue ( generator, completion )
+  ...
+  2. Let promiseCapability be ! NewPromiseCapability(%Promise%).
+  ...
+  9. Return promiseCapability.[[Promise]].
+
+includes: [propertyHelper.js]
+features: [async-iteration]
+---*/
+
+async function* g() {}
+var result = g().return()
+
+assert(result instanceof Promise)

test/built-ins/AsyncGeneratorPrototype/return/return-state-completed.js

+// Copyright 2018 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-asyncgenerator-prototype-return
+description: return() results in fullfilled promise when called on completed iterator
+info: |
+  AsyncGenerator.prototype.return ( value )
+  1. Let generator be the this value.
+  2. Let completion be Completion{[[Type]]: return, [[Value]]: value, [[Target]]: empty}.
+  3. Return ! AsyncGeneratorEnqueue(generator, completion).
+
+  AsyncGeneratorEnqueue ( generator, completion )
+  ...
+  8. If state is not "executing", then
+    a. Perform ! AsyncGeneratorResumeNext(generator).
+  ...
+
+  AsyncGeneratorResumeNext:
+  If completion.[[Type]] is throw, and generator.[[AsyncGeneratorState]] is
+  "completed"
+flags: [async]
+features: [async-iteration]
+---*/
+
+var g = async function*() {};
+
+var iter = g();
+iter.next().then(function(result) {
+  assert.sameValue(result.value, undefined);
+  assert.sameValue(result.done, true);
+
+  iter.return(42).then(function(result) {
+    assert.sameValue(result.value, 42)
+    assert.sameValue(result.done, true)
+  }).then($DONE, $DONE);
+
+}).catch($DONE);