Improve line iteration

test.js

@@ -1,6 +1,16 @@
 import test from 'ava';
 import nanoSpawn from './index.js';
 
+// TODO: replace with Array.fromAsync() after dropping support for Node <22.0.0
+const arrayFromAsync = async asyncIterable => {
+	const chunks = [];
+	for await (const chunk of asyncIterable) {
+		chunks.push(chunk);
+	}
+
+	return chunks;
+};
+
 test('can be awaited', async t => {
 	const result = await nanoSpawn('echo', ['🦄']);
 	// TODO
@@ -10,36 +20,51 @@ test('can be awaited', async t => {
 
 test('stdout produces correct output', async t => {
 	const result = nanoSpawn('echo', ['Hello\nWorld']);
-
-	const lines = [];
-	for await (const chunk of result.stdout) {
-		lines.push(chunk.toString());
-	}
-
+	const lines = await arrayFromAsync(result.stdout);
 	t.deepEqual(lines, ['Hello', 'World']);
 });
 
 test('stderr produces correct output', async t => {
 	const result = nanoSpawn('ls', ['non-existent-file']);
-
-	const lines = [];
-	for await (const line of result.stderr) {
-		lines.push(line);
-	}
-
+	const lines = await arrayFromAsync(result.stderr);
 	t.is(lines.length, 1);
 	t.regex(lines[0], /No such file/);
 });
 
 test('combines stdout and stderr correctly', async t => {
 	const result = nanoSpawn('bash', ['-c', 'echo "stdout\nstdout2"; echo "stderr\nstderr2" 1>&2']);
+	const lines = await arrayFromAsync(result);
+	t.deepEqual(lines, ['stdout', 'stderr', 'stdout2', 'stderr2']);
+});
 
-	const lines = [];
-	for await (const line of result) {
-		lines.push(line);
-	}
+test('stdout handles no newline at the end', async t => {
+	const result = nanoSpawn('node', ['-e', 'process.stdout.write("Hello\\nWorld")']);
+	const lines = await arrayFromAsync(result.stdout);
+	t.deepEqual(lines, ['Hello', 'World']);
+});
 
-	t.deepEqual(lines, ['stdout', 'stderr', 'stdout2', 'stderr2']);
+test('stdout handles newline at the end', async t => {
+	const result = nanoSpawn('node', ['-e', 'process.stdout.write("Hello\\nWorld\\n")']);
+	const lines = await arrayFromAsync(result.stdout);
+	t.deepEqual(lines, ['Hello', 'World']);
+});
+
+test('stdout handles 2 newlines at the end', async t => {
+	const result = nanoSpawn('node', ['-e', 'process.stdout.write("Hello\\nWorld\\n\\n")']);
+	const lines = await arrayFromAsync(result.stdout);
+	t.deepEqual(lines, ['Hello', 'World', '']);
+});
+
+test('stdout handles Windows newlines', async t => {
+	const result = nanoSpawn('node', ['-e', 'process.stdout.write("Hello\\r\\nWorld")']);
+	const lines = await arrayFromAsync(result.stdout);
+	t.deepEqual(lines, ['Hello', 'World']);
+});
+
+test('stdout handles Windows newline at the end', async t => {
+	const result = nanoSpawn('node', ['-e', 'process.stdout.write("Hello\\r\\nWorld\\r\\n")']);
+	const lines = await arrayFromAsync(result.stdout);
+	t.deepEqual(lines, ['Hello', 'World']);
 });
 
 test('rejects on error', async t => {

utilities.js

@@ -29,15 +29,13 @@ export async function * combineAsyncIterables(iterable1, iterable2) {
 	}
 }
 
-export async function * lineIterator(iterable) {
+export async function * lineIterator(stream) {
+	stream.setEncoding('utf8');
 	let buffer = '';
-	for await (const chunk of iterable) {
-		buffer += chunk;
-		const lines = buffer.split('\n');
+	for await (const chunk of stream) {
+		const lines = `${buffer}${chunk}`.split(/\r?\n/);
 		buffer = lines.pop(); // Keep last line in buffer as it may not be complete
-		for (const line of lines) {
-			yield line;
-		}
+		yield * lines;
 	}
 
 	if (buffer) {