explicit_resource_management.js
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explicit_resource_management.js
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	import { test, testDeep, summary } from './helpers.js';

	console.log('Explicit Resource Management Tests\n');

	test('Symbol.dispose exists', typeof Symbol.dispose, 'symbol');
	test('Symbol.asyncDispose exists', typeof Symbol.asyncDispose, 'symbol');
	test('SuppressedError constructor exists', typeof SuppressedError, 'function');

	const suppressed = new SuppressedError('error', 'suppressed', 'message');
	test('SuppressedError name', suppressed.name, 'SuppressedError');
	test('SuppressedError message', suppressed.message, 'message');
	test('SuppressedError error property', suppressed.error, 'error');
	test('SuppressedError suppressed property', suppressed.suppressed, 'suppressed');
	test('SuppressedError instanceof Error', suppressed instanceof Error, true);
	test('SuppressedError callable', SuppressedError('e', 's') instanceof SuppressedError, true);

	let stackLog = [];
	const stack = new DisposableStack();
	const used = {
	[Symbol.dispose]() {
	stackLog.push('use');
	}
	};
	test('DisposableStack use returns resource', stack.use(used), used);
	test(
	'DisposableStack adopt returns value',
	stack.adopt('value', value => stackLog.push('adopt:' + value)),
	'value'
	);
	test(
	'DisposableStack defer returns undefined',
	stack.defer(() => stackLog.push('defer')),
	undefined
	);
	test('DisposableStack move returns stack', stack.move() instanceof DisposableStack, true);

	const stack2 = new DisposableStack();
	stack2.use({
	[Symbol.dispose]() {
	stackLog.push('second use');
	}
	});
	stack2.adopt('second', value => stackLog.push(value));
	stack2.defer(() => stackLog.push('second defer'));
	stack2.dispose();
	testDeep('DisposableStack disposes LIFO', stackLog.slice(-3), ['second defer', 'second', 'second use']);

	let suppressedErr1 = new Error('first');
	let suppressedErr2 = new Error('second');
	let suppressedCaught;
	try {
	const throwingStack = new DisposableStack();
	throwingStack.use({
	[Symbol.dispose]() {
	throw suppressedErr2;
	}
	});
	throwingStack.use({
	[Symbol.dispose]() {
	throw suppressedErr1;
	}
	});
	throwingStack.dispose();
	} catch (e) {
	suppressedCaught = e;
	}
	test('DisposableStack suppression error', suppressedCaught.error, suppressedErr2);
	test('DisposableStack suppression suppressed', suppressedCaught.suppressed, suppressedErr1);

	let asyncLog = [];
	const asyncStack = new AsyncDisposableStack();
	const asyncResource = {
	async [Symbol.asyncDispose]() {
	asyncLog.push('use');
	}
	};
	test('AsyncDisposableStack use returns resource', asyncStack.use(asyncResource), asyncResource);
	test(
	'AsyncDisposableStack adopt returns value',
	asyncStack.adopt('value', async value => asyncLog.push('adopt:' + value)),
	'value'
	);
	test(
	'AsyncDisposableStack defer returns undefined',
	asyncStack.defer(async () => asyncLog.push('defer')),
	undefined
	);
	await asyncStack.disposeAsync();
	testDeep('AsyncDisposableStack disposes LIFO', asyncLog, ['defer', 'adopt:value', 'use']);

	function usingBlock(resource) {
	{
	using _ = resource;
	}
	}

	const usingResource = {
	disposed: false,
	[Symbol.dispose]() {
	this.disposed = true;
	}
	};
	usingBlock(usingResource);
	test('using block disposes', usingResource.disposed, true);

	function usingReturn(resource) {
	{
	using _ = resource;
	return 'done';
	}
	}

	const returnResource = {
	disposed: false,
	[Symbol.dispose]() {
	this.disposed = true;
	}
	};
	test('using return value', usingReturn(returnResource), 'done');
	test('using return disposes', returnResource.disposed, true);

	let throwingReturnCalls = 0;
	const throwingReturnError = new Error('dispose return');
	try {
	(function () {
	{
	using _ = {
	[Symbol.dispose]() {
	throwingReturnCalls++;
	throw throwingReturnError;
	}
	};
	return 'skipped';
	}
	})();
	} catch (e) {
	test('using return cleanup throws original error', e, throwingReturnError);
	}
	test('using return cleanup throws once', throwingReturnCalls, 1);

	function usingFunctionScope(resource) {
	using _ = resource;
	test('using function scope alive before return', resource.disposed, false);
	return 'function';
	}

	const functionScopeResource = {
	disposed: false,
	[Symbol.dispose]() {
	this.disposed = true;
	}
	};
	test('using function scope return value', usingFunctionScope(functionScopeResource), 'function');
	test('using function scope disposes on return', functionScopeResource.disposed, true);

	let breakResource;
	while (true) {
	{
	using _ = (breakResource = {
	disposed: false,
	[Symbol.dispose]() {
	this.disposed = true;
	}
	});
	break;
	}
	}
	test('using break disposes', breakResource.disposed, true);

	let continueResource;
	let continueCount = 0;
	while (continueCount++ < 1) {
	{
	using _ = (continueResource = {
	disposed: false,
	[Symbol.dispose]() {
	this.disposed = true;
	}
	});
	continue;
	}
	}
	test('using continue disposes', continueResource.disposed, true);

	async function awaitUsingBlock(resource) {
	{
	await using _ = resource;
	}
	}

	const awaitUsingResource = {
	disposed: false,
	async [Symbol.asyncDispose]() {
	this.disposed = true;
	}
	};
	await awaitUsingBlock(awaitUsingResource);
	test('await using block disposes', awaitUsingResource.disposed, true);

	async function awaitUsingReturn(resource) {
	{
	await using _ = resource;
	return 'async';
	}
	}

	const awaitReturnResource = {
	disposed: false,
	async [Symbol.asyncDispose]() {
	this.disposed = true;
	}
	};
	test('await using return value', await awaitUsingReturn(awaitReturnResource), 'async');
	test('await using return disposes', awaitReturnResource.disposed, true);

	let throwingAwaitReturnCalls = 0;
	const throwingAwaitReturnError = new Error('async dispose return');
	try {
	await (async function () {
	{
	await using _ = {
	async [Symbol.asyncDispose]() {
	throwingAwaitReturnCalls++;
	throw throwingAwaitReturnError;
	}
	};
	return 'skipped';
	}
	})();
	} catch (e) {
	test('await using return cleanup throws original error', e, throwingAwaitReturnError);
	}
	test('await using return cleanup throws once', throwingAwaitReturnCalls, 1);

	const forOfLog = [];
	for (using item of [
	{
	[Symbol.dispose]() {
	forOfLog.push('a');
	}
	},
	{
	[Symbol.dispose]() {
	forOfLog.push('b');
	}
	}
	]);
	testDeep('using for-of disposes each iteration', forOfLog, ['a', 'b']);

	const forOfBreakLog = [];
	for (using item of [
	{
	[Symbol.dispose]() {
	forOfBreakLog.push('break');
	}
	}
	]) {
	break;
	}
	testDeep('using for-of break disposes current item', forOfBreakLog, ['break']);

	const forOfThrowLog = [];
	try {
	for (using item of [
	{
	[Symbol.dispose]() {
	forOfThrowLog.push('throw');
	}
	}
	]) {
	throw new Error('body');
	}
	} catch (e) {
	test('using for-of body throw preserved', e.message, 'body');
	}
	testDeep('using for-of throw disposes current item', forOfThrowLog, ['throw']);

	const awaitForOfLog = [];
	for (await using item of [
	{
	async [Symbol.asyncDispose]() {
	awaitForOfLog.push('a');
	}
	},
	{
	async [Symbol.asyncDispose]() {
	awaitForOfLog.push('b');
	}
	}
	]);
	testDeep('await using for-of disposes each iteration', awaitForOfLog, ['a', 'b']);

	const awaitForOfBreakLog = [];
	for (await using item of [
	{
	async [Symbol.asyncDispose]() {
	awaitForOfBreakLog.push('break');
	}
	}
	]) {
	break;
	}
	testDeep('await using for-of break disposes current item', awaitForOfBreakLog, ['break']);

	const err1 = new Error('dispose 1');
	const err2 = new Error('dispose 2');
	const err3 = new Error('body');
	let usingSuppressed;
	try {
	{
	using _1 = {
	[Symbol.dispose]() {
	throw err1;
	}
	},
	_2 = {
	[Symbol.dispose]() {
	throw err2;
	}
	};
	throw err3;
	}
	} catch (e) {
	usingSuppressed = e;
	}

	test('using suppression outer error', usingSuppressed.error, err1);
	test('using suppression inner error', usingSuppressed.suppressed.error, err2);
	test('using suppression body error', usingSuppressed.suppressed.suppressed, err3);

	summary();

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