streams-encoding.js
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streams-encoding.js
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	import { test, testDeep, testThrows, summary } from './helpers.js';

	console.log('TextEncoderStream / TextDecoderStream Tests\n');

	test('TES typeof', typeof TextEncoderStream, 'function');
	test('TES toStringTag', Object.prototype.toString.call(new TextEncoderStream()), '[object TextEncoderStream]');

	testThrows('TES requires new', () => TextEncoderStream());

	const tes0 = new TextEncoderStream();
	test('TES encoding', tes0.encoding, 'utf-8');
	test('TES readable is ReadableStream', tes0.readable instanceof ReadableStream, true);
	test('TES writable is WritableStream', tes0.writable instanceof WritableStream, true);

	async function testTESBasic() {
	const tes = new TextEncoderStream();
	const writer = tes.writable.getWriter();
	const reader = tes.readable.getReader();
	writer.write('hello');
	const { value } = await reader.read();
	test('TES basic encode type', value instanceof Uint8Array, true);
	testDeep('TES basic encode value', Array.from(value), [104, 101, 108, 108, 111]);
	writer.close();
	}

	async function testTESEmpty() {
	const tes = new TextEncoderStream();
	const writer = tes.writable.getWriter();
	const reader = tes.readable.getReader();
	writer.write('a');
	writer.close();
	const { value } = await reader.read();
	testDeep('TES non-empty chunk', Array.from(value), [97]);
	const { done } = await reader.read();
	test('TES stream closes', done, true);
	}

	async function testTESMultiChunks() {
	const tes = new TextEncoderStream();
	const writer = tes.writable.getWriter();
	const reader = tes.readable.getReader();
	writer.write('abc');
	writer.write('def');
	const r1 = await reader.read();
	const r2 = await reader.read();
	testDeep('TES chunk1', Array.from(r1.value), [97, 98, 99]);
	testDeep('TES chunk2', Array.from(r2.value), [100, 101, 102]);
	}

	async function testTESUnicode() {
	const tes = new TextEncoderStream();
	const writer = tes.writable.getWriter();
	const reader = tes.readable.getReader();
	writer.write('café');
	const { value } = await reader.read();
	testDeep('TES unicode', Array.from(value), [99, 97, 102, 195, 169]);
	}

	async function testTESPipeThrough() {
	const rs = new ReadableStream({
	start(c) {
	c.enqueue('hello');
	c.close();
	}
	});
	const tes = new TextEncoderStream();
	const reader = rs.pipeThrough(tes).getReader();
	const { value } = await reader.read();
	test('TES pipeThrough type', value instanceof Uint8Array, true);
	testDeep('TES pipeThrough value', Array.from(value), [104, 101, 108, 108, 111]);
	}

	test('TDS typeof', typeof TextDecoderStream, 'function');
	test('TDS toStringTag', Object.prototype.toString.call(new TextDecoderStream()), '[object TextDecoderStream]');
	testThrows('TDS requires new', () => TextDecoderStream());

	const tds0 = new TextDecoderStream();
	test('TDS encoding default', tds0.encoding, 'utf-8');
	test('TDS fatal default', tds0.fatal, false);
	test('TDS ignoreBOM default', tds0.ignoreBOM, false);
	test('TDS readable is ReadableStream', tds0.readable instanceof ReadableStream, true);
	test('TDS writable is WritableStream', tds0.writable instanceof WritableStream, true);

	const tds1 = new TextDecoderStream('utf-8', { fatal: true, ignoreBOM: true });
	test('TDS fatal option', tds1.fatal, true);
	test('TDS ignoreBOM option', tds1.ignoreBOM, true);

	testThrows('TDS invalid encoding', () => new TextDecoderStream('invalid-encoding'));

	async function testTDSBasic() {
	const tds = new TextDecoderStream();
	const writer = tds.writable.getWriter();
	const reader = tds.readable.getReader();
	writer.write(new Uint8Array([104, 101, 108, 108, 111]));
	const { value } = await reader.read();
	test('TDS basic decode', value, 'hello');
	writer.close();
	}

	async function testTDSMultiChunks() {
	const tds = new TextDecoderStream();
	const writer = tds.writable.getWriter();
	const reader = tds.readable.getReader();
	writer.write(new Uint8Array([97, 98, 99]));
	writer.write(new Uint8Array([100, 101, 102]));
	const r1 = await reader.read();
	const r2 = await reader.read();
	test('TDS chunk1', r1.value, 'abc');
	test('TDS chunk2', r2.value, 'def');
	}

	async function testTDSSplitMultibyte() {
	const tds = new TextDecoderStream();
	const writer = tds.writable.getWriter();
	const reader = tds.readable.getReader();
	writer.write(new Uint8Array([99, 97, 102, 0xc3]));
	writer.write(new Uint8Array([0xa9]));
	writer.close();
	const chunks = [];
	while (true) {
	const { value, done } = await reader.read();
	if (done) break;
	if (value) chunks.push(value);
	}
	test('TDS split multibyte', chunks.join(''), 'café');
	}

	async function testTDSPipeThrough() {
	const rs = new ReadableStream({
	start(c) {
	c.enqueue(new Uint8Array([104, 101, 108, 108, 111]));
	c.close();
	}
	});
	const tds = new TextDecoderStream();
	const reader = rs.pipeThrough(tds).getReader();
	const { value } = await reader.read();
	test('TDS pipeThrough', value, 'hello');
	}

	async function testRoundTrip() {
	const rs = new ReadableStream({
	start(c) {
	c.enqueue('hello world');
	c.close();
	}
	});
	const reader = rs.pipeThrough(new TextEncoderStream()).pipeThrough(new TextDecoderStream()).getReader();
	const { value } = await reader.read();
	test('encode→decode roundtrip', value, 'hello world');
	}

	async function testTDSUTF16LE() {
	const tds = new TextDecoderStream('utf-16le');
	test('TDS utf-16le encoding', tds.encoding, 'utf-16le');
	const writer = tds.writable.getWriter();
	const reader = tds.readable.getReader();
	writer.write(new Uint8Array([0x68, 0x00, 0x69, 0x00]));
	const { value } = await reader.read();
	test('TDS utf-16le decode', value, 'hi');
	}

	await testTESBasic();
	await testTESEmpty();
	await testTESMultiChunks();
	await testTESUnicode();
	await testTESPipeThrough();
	await testTDSBasic();
	await testTDSMultiChunks();
	await testTDSSplitMultibyte();
	await testTDSPipeThrough();
	await testRoundTrip();
	await testTDSUTF16LE();

	summary();

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