[esnext] prototype runtime implementation for async functions

test/mjsunit/harmony/async-await-basic.js

Index: test/mjsunit/harmony/async-await-basic.js
diff --git a/test/mjsunit/harmony/async-await-basic.js b/test/mjsunit/harmony/async-await-basic.js
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+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-async-await --allow-natives-syntax
+
+// Do not install `AsyncFunction` constructor on global object
+
+function assertThrowsAsync(run, errorType, message) {
+  var actual;
+  var hadValue = false;
+  var hadError = false;
+  var promise = run();
+
+  if (typeof promise !== "object" || typeof promise.then !== "function") {
+    throw new MjsUnitAssertionError(
+        "Expected " + run.toString() +
+        " to return a Promise, but it returned " + PrettyPrint(promise));
+  }
+
+  promise.then(function(value) { hadValue = true; actual = value; },
+               function(error) { hadError = true; actual = error; });
+
+  assertFalse(hadValue || hadError);
+
+  %RunMicrotasks();
+
+  if (!hadError) {
+    throw new MjsUnitAssertionError(
+        "Expected " + run + "() to throw " + errorType.name +
+        ", but did not throw.");
+  }
+  if (!(actual instanceof errorType))
+    throw new MjsUnitAssertionError(
+        "Expected " + run + "() to throw " + errorType.name +
+        ", but threw '" + actual + "'");
+  if (message !== void 0 && actual.message !== message)
+    throw new MjsUnitAssertionError(
+        "Expected " + run + "() to throw '" + message + "', but threw '" +
+        actual.message + "'");
+};
+
+function assertEqualsAsync(expected, run, msg) {
+  var actual;
+  var hadValue = false;
+  var hadError = false;
+  var promise = run();
+
+  if (typeof promise !== "object" || typeof promise.then !== "function") {
+    throw new MjsUnitAssertionError(
+        "Expected " + run.toString() +
+        " to return a Promise, but it returned " + PrettyPrint(promise));
+  }
+
+  promise.then(function(value) { hadValue = true; actual = value; },
+               function(error) { hadError = true; actual = error; });
+
+  assertFalse(hadValue || hadError);
+
+  %RunMicrotasks();
+
+  if (hadError) throw actual;
+
+  assertTrue(
+      hadValue, "Expected '" + run.toString() + "' to produce a value");
+
+  assertEquals(expected, actual, msg);
+};
+
+assertEquals(undefined, this.AsyncFunction);
+let AsyncFunction = (async function() {}).constructor;
+
+// Let functionPrototype be the intrinsic object %AsyncFunctionPrototype%.
+async function asyncFunctionForProto() {}
+assertEquals(AsyncFunction.prototype,
+             Object.getPrototypeOf(asyncFunctionForProto));
+assertEquals(AsyncFunction.prototype,
+             Object.getPrototypeOf(async function() {}));
+assertEquals(AsyncFunction.prototype, Object.getPrototypeOf(async () => {}));
+assertEquals(AsyncFunction.prototype,
+             Object.getPrototypeOf({ async method() {} }.method));
+assertEquals(AsyncFunction.prototype, Object.getPrototypeOf(AsyncFunction()));
+assertEquals(AsyncFunction.prototype,
+             Object.getPrototypeOf(new AsyncFunction()));
+
+// AsyncFunctionCreate does not produce an object with a Prototype
+assertEquals(undefined, asyncFunctionForProto.prototype);
+assertEquals(false, asyncFunctionForProto.hasOwnProperty("prototype"));
+assertEquals(undefined, (async function() {}).prototype);
+assertEquals(false, (async function() {}).hasOwnProperty("prototype"));
+assertEquals(undefined, (async() => {}).prototype);
+assertEquals(false, (async() => {}).hasOwnProperty("prototype"));
+assertEquals(undefined, ({ async method() {} }).method.prototype);
+assertEquals(false, ({ async method() {} }).method.hasOwnProperty("prototype"));
+assertEquals(undefined, AsyncFunction().prototype);
+assertEquals(false, AsyncFunction().hasOwnProperty("prototype"));
+assertEquals(undefined, (new AsyncFunction()).prototype);
+assertEquals(false, (new AsyncFunction()).hasOwnProperty("prototype"));
+
+assertEquals(1, async function(a) { await 1; }.length);
+assertEquals(2, async function(a, b) { await 1; }.length);
+assertEquals(1, async function(a, b = 2) { await 1; }.length);
+assertEquals(2, async function(a, b, ...c) { await 1; }.length);
+
+assertEquals(1, (async(a) => await 1).length);
+assertEquals(2, (async(a, b) => await 1).length);
+assertEquals(1, (async(a, b = 2) => await 1).length);
+assertEquals(2, (async(a, b, ...c) => await 1).length);
+
+assertEquals(1, ({ async f(a) { await 1; } }).f.length);
+assertEquals(2, ({ async f(a, b) { await 1; } }).f.length);
+assertEquals(1, ({ async f(a, b = 2) { await 1; } }).f.length);
+assertEquals(2, ({ async f(a, b, ...c) { await 1; } }).f.length);
+
+assertEquals(1, AsyncFunction("a", "await 1").length);
+assertEquals(2, AsyncFunction("a", "b", "await 1").length);
+assertEquals(1, AsyncFunction("a", "b = 2", "await 1").length);
+assertEquals(2, AsyncFunction("a", "b", "...c", "await 1").length);
+
+assertEquals(1, (new AsyncFunction("a", "await 1")).length);
+assertEquals(2, (new AsyncFunction("a", "b", "await 1")).length);
+assertEquals(1, (new AsyncFunction("a", "b = 2", "await 1")).length);
+assertEquals(2, (new AsyncFunction("a", "b", "...c", "await 1")).length);
+
+// AsyncFunction.prototype[ @@toStringTag ]
+var descriptor =
+    Object.getOwnPropertyDescriptor(AsyncFunction.prototype,
+                                    Symbol.toStringTag);
+assertEquals("AsyncFunction", descriptor.value);
+assertEquals(false, descriptor.enumerable);
+assertEquals(false, descriptor.writable);
+assertEquals(true, descriptor.configurable);
+
+assertEquals(1, AsyncFunction.length);
+
+// Let F be ! FunctionAllocate(functionPrototype, Strict, "non-constructor")
+async function asyncNonConstructorDecl() {}
+assertThrows(
+    () => new asyncNonConstructorDecl(), TypeError);
+assertThrows(
+    () => new (async function() {}), TypeError);
+assertThrows(
+    () => new ({ async nonConstructor() {} }).nonConstructor(), TypeError);
+assertThrows(
+    () => new (() => "not a constructor!"), TypeError);
+assertThrows(
+    () => new (AsyncFunction()), TypeError);
+assertThrows(
+    () => new (new AsyncFunction()), TypeError);
+
+// Normal completion
+async function asyncDecl() { return "test"; }
+assertEqualsAsync("test", asyncDecl);
+assertEqualsAsync("test2", async function() { return "test2"; });
+assertEqualsAsync("test3", async () => "test3");
+assertEqualsAsync("test4", () => ({ async f() { return "test4"; } }).f());
+assertEqualsAsync("test5", () => AsyncFunction("no", "return 'test' + no;")(5));
+assertEqualsAsync("test6",
+                  () => (new AsyncFunction("no", "return 'test' + no;"))(6));
+
+class MyError extends Error {};
+
+// Throw completion
+async function asyncDeclThrower(e) { throw new MyError(e); }
+assertThrowsAsync(() => asyncDeclThrower("boom!"), MyError, "boom!");
+assertThrowsAsync(
+  () => (async function(e) { throw new MyError(e); })("boom!!!"),
+  MyError, "boom!!!");
+assertThrowsAsync(
+  () => (async e => { throw new MyError(e) })("boom!!"), MyError, "boom!!");
+assertThrowsAsync(
+  () => ({ async thrower(e) { throw new MyError(e); } }).thrower("boom!1!"),
+  MyError, "boom!1!");
+assertThrowsAsync(
+  () => AsyncFunction("msg", "throw new MyError(msg)")("boom!2!!"),
+  MyError, "boom!2!!");
+assertThrowsAsync(
+  () => (new AsyncFunction("msg", "throw new MyError(msg)"))("boom!2!!!"),
+  MyError, "boom!2!!!");
+
+function resolveLater(value) { return Promise.resolve(value); }
+function rejectLater(error) { return Promise.reject(error); }
+
+// Resume after Normal completion
+var log = [];
+async function resumeAfterNormal(value) {
+  log.push("start:" + value);
+  value = await resolveLater(value + 1);
+  log.push("resume:" + value);
+  value = await resolveLater(value + 1);
+  log.push("resume:" + value);
+  return value + 1;
+}
+
+assertEqualsAsync(4, () => resumeAfterNormal(1));
+assertEquals("start:1 resume:2 resume:3", log.join(" "));
+
+var O = {
+  async resumeAfterNormal(value) {
+    log.push("start:" + value);
+    value = await resolveLater(value + 1);
+    log.push("resume:" + value);
+    value = await resolveLater(value + 1);
+    log.push("resume:" + value);
+    return value + 1;
+  }
+};
+log = [];
+assertEqualsAsync(5, () => O.resumeAfterNormal(2));
+assertEquals("start:2 resume:3 resume:4", log.join(" "));
+
+var resumeAfterNormalArrow = async (value) => {
+  log.push("start:" + value);
+  value = await resolveLater(value + 1);
+  log.push("resume:" + value);
+  value = await resolveLater(value + 1);
+  log.push("resume:" + value);
+  return value + 1;
+};
+log = [];
+assertEqualsAsync(6, () => resumeAfterNormalArrow(3));
+assertEquals("start:3 resume:4 resume:5", log.join(" "));
+
+var resumeAfterNormalEval = AsyncFunction("value", `
+    log.push("start:" + value);
+    value = await resolveLater(value + 1);
+    log.push("resume:" + value);
+    value = await resolveLater(value + 1);
+    log.push("resume:" + value);
+    return value + 1;`);
+log = [];
+assertEqualsAsync(7, () => resumeAfterNormalEval(4));
+assertEquals("start:4 resume:5 resume:6", log.join(" "));
+
+var resumeAfterNormalNewEval = new AsyncFunction("value", `
+    log.push("start:" + value);
+    value = await resolveLater(value + 1);
+    log.push("resume:" + value);
+    value = await resolveLater(value + 1);
+    log.push("resume:" + value);
+    return value + 1;`);
+log = [];
+assertEqualsAsync(8, () => resumeAfterNormalNewEval(5));
+assertEquals("start:5 resume:6 resume:7", log.join(" "));
+
+// Resume after Throw completion
+async function resumeAfterThrow(value) {
+  log.push("start:" + value);
+  try {
+    value = await rejectLater("throw1");
+  } catch (e) {
+    log.push("resume:" + e);
+  }
+  try {
+    value = await rejectLater("throw2");
+  } catch (e) {
+    log.push("resume:" + e);
+  }
+  return value + 1;
+}
+
+log = [];
+assertEqualsAsync(2, () => resumeAfterThrow(1));
+assertEquals("start:1 resume:throw1 resume:throw2", log.join(" "));
+
+var O = {
+  async resumeAfterThrow(value) {
+    log.push("start:" + value);
+    try {
+      value = await rejectLater("throw1");
+    } catch (e) {
+      log.push("resume:" + e);
+    }
+    try {
+      value = await rejectLater("throw2");
+    } catch (e) {
+      log.push("resume:" + e);
+    }
+    return value + 1;
+  }
+}
+log = [];
+assertEqualsAsync(3, () => O.resumeAfterThrow(2));
+assertEquals("start:2 resume:throw1 resume:throw2", log.join(" "));
+
+var resumeAfterThrowArrow = async (value) => {
+  log.push("start:" + value);
+  try {
+    value = await rejectLater("throw1");
+  } catch (e) {
+    log.push("resume:" + e);
+  }
+  try {
+    value = await rejectLater("throw2");
+  } catch (e) {
+    log.push("resume:" + e);
+  }
+ return value + 1;
+};
+
+log = [];
+
+assertEqualsAsync(4, () => resumeAfterThrowArrow(3));
+assertEquals("start:3 resume:throw1 resume:throw2", log.join(" "));
+
+var resumeAfterThrowEval = AsyncFunction("value", `
+    log.push("start:" + value);
+    try {
+      value = await rejectLater("throw1");
+    } catch (e) {
+      log.push("resume:" + e);
+    }
+    try {
+      value = await rejectLater("throw2");
+    } catch (e) {
+      log.push("resume:" + e);
+    }
+    return value + 1;`);
+log = [];
+assertEqualsAsync(5, () => resumeAfterThrowEval(4));
+assertEquals("start:4 resume:throw1 resume:throw2", log.join(" "));
+
+var resumeAfterThrowNewEval = new AsyncFunction("value", `
+    log.push("start:" + value);
+    try {
+      value = await rejectLater("throw1");
+    } catch (e) {
+      log.push("resume:" + e);
+    }
+    try {
+      value = await rejectLater("throw2");
+    } catch (e) {
+      log.push("resume:" + e);
+    }
+    return value + 1;`);
+log = [];
+assertEqualsAsync(6, () => resumeAfterThrowNewEval(5));
+assertEquals("start:5 resume:throw1 resume:throw2", log.join(" "));