Add tests for the asyncItems argument to Array.fromAsync. (#3754)

Co-authored-by: Philip Chimento <pchimento@igalia.com>

harness/temporalHelpers.js

@@ -20,6 +20,7 @@ function formatPropertyName(propertyKey, objectName = "") {
     case "number":
       return `${objectName}[${propertyKey}]`;
     default:
+      // TODO: check if propertyKey is an integer index.
       return objectName ? `${objectName}.${propertyKey}` : propertyKey;
   }
 }

test/built-ins/Array/fromAsync/asyncitems-array-add-to-empty.js

@@ -0,0 +1,44 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync respects array mutation
+info: |
+  Array.fromAsync
+    3.j.ii.3. Let next be ? Await(IteratorStep(iteratorRecord)).
+
+  IteratorStep
+    1. Let result be ? IteratorNext(iteratorRecord).
+
+  IteratorNext
+    1.a. Let result be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]]).
+
+  %AsyncFromSyncIteratorPrototype%.next
+    6.a. Let result be Completion(IteratorNext(syncIteratorRecord)).
+
+  IteratorNext
+    1.a. Let result be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]]).
+
+  Array.prototype [ @@iterator ] ( )
+  Array.prototype.values ( )
+    2. Return CreateArrayIterator(O, value).
+
+  CreateArrayIterator
+    1.b.iii. If index ≥ len, return NormalCompletion(undefined).
+includes: [asyncHelpers.js, compareArray.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  const items = [];
+  const promise = Array.fromAsync(items);
+  // By the time we get here, the first next() call has already happened, and returned
+  // { done: true }. We then return from the loop in Array.fromAsync 3.j.ii. with the empty array,
+  // and the following line no longer affects that.
+  items.push(7);
+  const result = await promise;
+  assert.compareArray(result, []);
+});

test/built-ins/Array/fromAsync/asyncitems-array-add-to-singleton.js

@@ -0,0 +1,43 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync respects array mutation
+info: |
+  Array.fromAsync
+    3.j.ii.3. Let next be ? Await(IteratorStep(iteratorRecord)).
+
+  IteratorStep
+    1. Let result be ? IteratorNext(iteratorRecord).
+
+  IteratorNext
+    1.a. Let result be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]]).
+
+  %AsyncFromSyncIteratorPrototype%.next
+    6.a. Let result be Completion(IteratorNext(syncIteratorRecord)).
+
+  IteratorNext
+    1.a. Let result be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]]).
+
+  Array.prototype [ @@iterator ] ( )
+  Array.prototype.values ( )
+    2. Return CreateArrayIterator(O, value).
+
+  CreateArrayIterator
+    1.b.iii. If index ≥ len, return NormalCompletion(undefined).
+includes: [asyncHelpers.js, compareArray.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  const items = [1];
+  const promise = Array.fromAsync(items);
+  // At this point, the first element of `items` has been read, but the iterator will take other
+  // changes into account.
+  items.push(7);
+  const result = await promise;
+  assert.compareArray(result, [1, 7]);
+});

test/built-ins/Array/fromAsync/asyncitems-array-add.js

@@ -0,0 +1,43 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync respects array mutation
+info: |
+  Array.fromAsync
+    3.j.ii.3. Let next be ? Await(IteratorStep(iteratorRecord)).
+
+  IteratorStep
+    1. Let result be ? IteratorNext(iteratorRecord).
+
+  IteratorNext
+    1.a. Let result be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]]).
+
+  %AsyncFromSyncIteratorPrototype%.next
+    6.a. Let result be Completion(IteratorNext(syncIteratorRecord)).
+
+  IteratorNext
+    1.a. Let result be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]]).
+
+  Array.prototype [ @@iterator ] ( )
+  Array.prototype.values ( )
+    2. Return CreateArrayIterator(O, value).
+
+  CreateArrayIterator
+    1.b.iii. If index ≥ len, return NormalCompletion(undefined).
+includes: [asyncHelpers.js, compareArray.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  const items = [1, 2, 3];
+  const promise = Array.fromAsync(items);
+  // At this point, the first element of `items` has been read, but the iterator will take other
+  // changes into account.
+  items.push(4);
+  const result = await promise;
+  assert.compareArray(result, [1, 2, 3, 4]);
+});

test/built-ins/Array/fromAsync/asyncitems-array-mutate.js

@@ -0,0 +1,44 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync respects array mutation
+info: |
+  Array.fromAsync
+    3.j.ii.3. Let next be ? Await(IteratorStep(iteratorRecord)).
+
+  IteratorStep
+    1. Let result be ? IteratorNext(iteratorRecord).
+
+  IteratorNext
+    1.a. Let result be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]]).
+
+  %AsyncFromSyncIteratorPrototype%.next
+    6.a. Let result be Completion(IteratorNext(syncIteratorRecord)).
+
+  IteratorNext
+    1.a. Let result be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]]).
+
+  Array.prototype [ @@iterator ] ( )
+  Array.prototype.values ( )
+    2. Return CreateArrayIterator(O, value).
+
+  CreateArrayIterator
+    1.b.iii. If index ≥ len, return NormalCompletion(undefined).
+includes: [asyncHelpers.js, compareArray.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  const items = [1, 2, 3];
+  const promise = Array.fromAsync(items);
+  // At this point, the first element of `items` has been read, but the iterator will take other
+  // changes into account.
+  items[0] = 7;
+  items[1] = 8;
+  const result = await promise;
+  assert.compareArray(result, [1, 8, 3]);
+});

test/built-ins/Array/fromAsync/asyncitems-array-remove.js

@@ -0,0 +1,43 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync respects array mutation
+info: |
+  Array.fromAsync
+    3.j.ii.3. Let next be ? Await(IteratorStep(iteratorRecord)).
+
+  IteratorStep
+    1. Let result be ? IteratorNext(iteratorRecord).
+
+  IteratorNext
+    1.a. Let result be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]]).
+
+  %AsyncFromSyncIteratorPrototype%.next
+    6.a. Let result be Completion(IteratorNext(syncIteratorRecord)).
+
+  IteratorNext
+    1.a. Let result be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]]).
+
+  Array.prototype [ @@iterator ] ( )
+  Array.prototype.values ( )
+    2. Return CreateArrayIterator(O, value).
+
+  CreateArrayIterator
+    1.b.iii. If index ≥ len, return NormalCompletion(undefined).
+includes: [asyncHelpers.js, compareArray.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  const items = [1, 2, 3];
+  const promise = Array.fromAsync(items);
+  // At this point, the first element of `items` has been read, but the iterator will take other
+  // changes into account.
+  items.pop();
+  const result = await promise;
+  assert.compareArray(result, [1, 2]);
+});

test/built-ins/Array/fromAsync/asyncitems-arraybuffer.js

@@ -0,0 +1,17 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync doesn't special-case ArrayBuffer
+includes: [asyncHelpers.js, compareArray.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  const items = new ArrayBuffer(7);
+  const result = await Array.fromAsync(items);
+  assert.compareArray(result, []);
+});

test/built-ins/Array/fromAsync/asyncitems-arraylike-promise.js

@@ -0,0 +1,31 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync tries the various properties in order and awaits promises
+includes: [asyncHelpers.js, compareArray.js, temporalHelpers.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  const actual = [];
+  const items = TemporalHelpers.propertyBagObserver(actual, {
+    length: 2,
+    0: Promise.resolve(2),
+    1: Promise.resolve(1),
+  }, "items");
+  const result = await Array.fromAsync(items);
+  assert.compareArray(result, [2, 1]);
+  assert.compareArray(actual, [
+    "get items[Symbol.asyncIterator]",
+    "get items[Symbol.iterator]",
+    "get items.length",
+    "get items.length.valueOf",
+    "call items.length.valueOf",
+    "get items.0",
+    "get items.1",
+  ]);
+});

test/built-ins/Array/fromAsync/asyncitems-asynciterator-exists.js

@@ -0,0 +1,32 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync tries the various properties in order
+includes: [asyncHelpers.js, compareArray.js, temporalHelpers.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  async function * asyncGen() {
+    for (let i = 0; i < 4; i++) {
+      yield Promise.resolve(i * 2);
+    }
+  }
+
+  const actual = [];
+  const items = {};
+  TemporalHelpers.observeProperty(actual, items, Symbol.asyncIterator, asyncGen, "items");
+  TemporalHelpers.observeProperty(actual, items, Symbol.iterator, undefined, "items");
+  TemporalHelpers.observeProperty(actual, items, "length", 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 0, 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 1, 1, "items");
+  const result = await Array.fromAsync(items);
+  assert.compareArray(result, [0, 2, 4, 6]);
+  assert.compareArray(actual, [
+    "get items[Symbol.asyncIterator]",
+  ]);
+});

test/built-ins/Array/fromAsync/asyncitems-asynciterator-not-callable.js

@@ -0,0 +1,19 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync rejects if the @@asyncIterator property is not callable
+includes: [asyncHelpers.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  for (const v of [true, "", Symbol(), 1, 1n, {}]) {
+    await assert.throwsAsync(TypeError,
+      () => Array.fromAsync({ [Symbol.asyncIterator]: v }),
+      `@@asyncIterator = ${typeof v}`);
+  }
+});

test/built-ins/Array/fromAsync/asyncitems-asynciterator-null.js

@@ -0,0 +1,30 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync tries the various properties in order
+includes: [asyncHelpers.js, compareArray.js, temporalHelpers.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  const actual = [];
+  const items = {};
+  TemporalHelpers.observeProperty(actual, items, Symbol.asyncIterator, null, "items");
+  TemporalHelpers.observeProperty(actual, items, Symbol.iterator, undefined, "items");
+  TemporalHelpers.observeProperty(actual, items, "length", 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 0, 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 1, 1, "items");
+  const result = await Array.fromAsync(items);
+  assert.compareArray(result, [2, 1]);
+  assert.compareArray(actual, [
+    "get items[Symbol.asyncIterator]",
+    "get items[Symbol.iterator]",
+    "get items.length",
+    "get items[0]",
+    "get items[1]",
+  ]);
+});

test/built-ins/Array/fromAsync/asyncitems-asynciterator-sync.js

@@ -0,0 +1,32 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync handles a sync iterator returned from @@asyncIterator
+includes: [asyncHelpers.js, compareArray.js, temporalHelpers.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  function * syncGen() {
+    for (let i = 0; i < 4; i++) {
+      yield i * 2;
+    }
+  }
+
+  const actual = [];
+  const items = {};
+  TemporalHelpers.observeProperty(actual, items, Symbol.asyncIterator, syncGen, "items");
+  TemporalHelpers.observeProperty(actual, items, Symbol.iterator, undefined, "items");
+  TemporalHelpers.observeProperty(actual, items, "length", 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 0, 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 1, 1, "items");
+  const result = await Array.fromAsync(items);
+  assert.compareArray(result, [0, 2, 4, 6]);
+  assert.compareArray(actual, [
+    "get items[Symbol.asyncIterator]",
+  ]);
+});

test/built-ins/Array/fromAsync/asyncitems-asynciterator-throws.js

@@ -0,0 +1,16 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync rejects if getting the @@asyncIterator property throws
+includes: [asyncHelpers.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  await assert.throwsAsync(Test262Error,
+    () => Array.fromAsync({ get [Symbol.asyncIterator]() { throw new Test262Error() } }));
+});

test/built-ins/Array/fromAsync/asyncitems-bigint.js

@@ -0,0 +1,20 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync treats a BigInt as an array-like
+includes: [asyncHelpers.js, compareArray.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  BigInt.prototype.length = 2;
+  BigInt.prototype[0] = 1;
+  BigInt.prototype[1] = 2;
+
+  const result = await Array.fromAsync(1n);
+  assert.compareArray(result, [1, 2]);
+});

test/built-ins/Array/fromAsync/asyncitems-boolean.js

@@ -0,0 +1,20 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync treats a boolean as an array-like
+includes: [asyncHelpers.js, compareArray.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  Boolean.prototype.length = 2;
+  Boolean.prototype[0] = 1;
+  Boolean.prototype[1] = 2;
+
+  const result = await Array.fromAsync(true);
+  assert.compareArray(result, [1, 2]);
+});

test/built-ins/Array/fromAsync/asyncitems-function.js

@@ -0,0 +1,21 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync treats a function as an array-like, reading elements up to fn.length
+includes: [asyncHelpers.js, compareArray.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  const fn = function(a, b) {};
+  fn[0] = 1;
+  fn[1] = 2;
+  fn[2] = 3;
+
+  const result = await Array.fromAsync(fn);
+  assert.compareArray(result, [1, 2]);
+});

test/built-ins/Array/fromAsync/asyncitems-iterator-exists.js

@@ -0,0 +1,33 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync handles a sync iterator returned from @@iterator
+includes: [asyncHelpers.js, compareArray.js, temporalHelpers.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  function * syncGen() {
+    for (let i = 0; i < 4; i++) {
+      yield i * 2;
+    }
+  }
+
+  const actual = [];
+  const items = {};
+  TemporalHelpers.observeProperty(actual, items, Symbol.asyncIterator, undefined, "items");
+  TemporalHelpers.observeProperty(actual, items, Symbol.iterator, syncGen, "items");
+  TemporalHelpers.observeProperty(actual, items, "length", 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 0, 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 1, 1, "items");
+  const result = await Array.fromAsync(items);
+  assert.compareArray(result, [0, 2, 4, 6]);
+  assert.compareArray(actual, [
+    "get items[Symbol.asyncIterator]",
+    "get items[Symbol.iterator]",
+  ]);
+});

test/built-ins/Array/fromAsync/asyncitems-iterator-not-callable.js

@@ -0,0 +1,19 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync rejects if the @@iterator property is not callable
+includes: [asyncHelpers.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  for (const v of [true, "", Symbol(), 1, 1n, {}]) {
+    await assert.throwsAsync(TypeError,
+      () => Array.fromAsync({ [Symbol.iterator]: v }),
+      `@@iterator = ${typeof v}`);
+  }
+});

test/built-ins/Array/fromAsync/asyncitems-iterator-null.js

@@ -0,0 +1,30 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync tries the various properties in order
+includes: [asyncHelpers.js, compareArray.js, temporalHelpers.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  const actual = [];
+  const items = {};
+  TemporalHelpers.observeProperty(actual, items, Symbol.asyncIterator, undefined, "items");
+  TemporalHelpers.observeProperty(actual, items, Symbol.iterator, null, "items");
+  TemporalHelpers.observeProperty(actual, items, "length", 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 0, 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 1, 1, "items");
+  const result = await Array.fromAsync(items);
+  assert.compareArray(result, [2, 1]);
+  assert.compareArray(actual, [
+    "get items[Symbol.asyncIterator]",
+    "get items[Symbol.iterator]",
+    "get items.length",
+    "get items[0]",
+    "get items[1]",
+  ]);
+});

test/built-ins/Array/fromAsync/asyncitems-iterator-promise.js

@@ -0,0 +1,33 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync handles an async iterator returned from @@iterator
+includes: [asyncHelpers.js, compareArray.js, temporalHelpers.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  function * asyncGen() {
+    for (let i = 0; i < 4; i++) {
+      yield Promise.resolve(i * 2);
+    }
+  }
+
+  const actual = [];
+  const items = {};
+  TemporalHelpers.observeProperty(actual, items, Symbol.asyncIterator, undefined, "items");
+  TemporalHelpers.observeProperty(actual, items, Symbol.iterator, asyncGen, "items");
+  TemporalHelpers.observeProperty(actual, items, "length", 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 0, 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 1, 1, "items");
+  const result = await Array.fromAsync(items);
+  assert.compareArray(result, [0, 2, 4, 6]);
+  assert.compareArray(actual, [
+    "get items[Symbol.asyncIterator]",
+    "get items[Symbol.iterator]",
+  ]);
+});

test/built-ins/Array/fromAsync/asyncitems-iterator-throws.js

@@ -0,0 +1,16 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync rejects if getting the @@iterator property throws
+includes: [asyncHelpers.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  await assert.throwsAsync(Test262Error,
+    () => Array.fromAsync({ get [Symbol.iterator]() { throw new Test262Error() } }));
+});

test/built-ins/Array/fromAsync/asyncitems-null-undefined.js

@@ -0,0 +1,18 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync rejects with a TypeError if the asyncItems argument is null or undefined
+info: |
+  3.c. Let usingAsyncIterator be ? GetMethod(asyncItems, @@asyncIterator).
+includes: [asyncHelpers.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  await assert.throwsAsync(TypeError, () => Array.fromAsync(null), "null asyncItems");
+  await assert.throwsAsync(TypeError, () => Array.fromAsync(undefined), "undefined asyncItems");
+});

test/built-ins/Array/fromAsync/asyncitems-number.js

@@ -0,0 +1,20 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync treats a Number as an array-like
+includes: [asyncHelpers.js, compareArray.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  Number.prototype.length = 2;
+  Number.prototype[0] = 1;
+  Number.prototype[1] = 2;
+
+  const result = await Array.fromAsync(1);
+  assert.compareArray(result, [1, 2]);
+});

test/built-ins/Array/fromAsync/asyncitems-operations.js

@@ -0,0 +1,30 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync tries the various properties in order
+includes: [asyncHelpers.js, compareArray.js, temporalHelpers.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  const actual = [];
+  const items = {};
+  TemporalHelpers.observeProperty(actual, items, Symbol.asyncIterator, undefined, "items");
+  TemporalHelpers.observeProperty(actual, items, Symbol.iterator, undefined, "items");
+  TemporalHelpers.observeProperty(actual, items, "length", 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 0, 2, "items");
+  TemporalHelpers.observeProperty(actual, items, 1, 1, "items");
+  const result = await Array.fromAsync(items);
+  assert.compareArray(result, [2, 1]);
+  assert.compareArray(actual, [
+    "get items[Symbol.asyncIterator]",
+    "get items[Symbol.iterator]",
+    "get items.length",
+    "get items[0]",
+    "get items[1]",
+  ]);
+});

test/built-ins/Array/fromAsync/asyncitems-string.js

@@ -0,0 +1,16 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync iterates over a string
+includes: [asyncHelpers.js, compareArray.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  const result = await Array.fromAsync("test");
+  assert.compareArray(result, ["t", "e", "s", "t"]);
+});

test/built-ins/Array/fromAsync/asyncitems-symbol.js

@@ -0,0 +1,20 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.fromasync
+description: >
+  Array.fromAsync treats a Symbol as an array-like
+includes: [asyncHelpers.js, compareArray.js]
+flags: [async]
+features: [Array.fromAsync]
+---*/
+
+asyncTest(async function () {
+  Symbol.prototype.length = 2;
+  Symbol.prototype[0] = 1;
+  Symbol.prototype[1] = 2;
+
+  const result = await Array.fromAsync(Symbol());
+  assert.compareArray(result, [1, 2]);
+});