Improve cleanup option (code quality, tests, documentation)

fixtures/sub-process

@@ -3,5 +3,6 @@
 const execa = require('..');
 
 const cleanup = process.argv[2] === 'true';
-const subprocess = execa('node', ['./fixtures/forever'], {cleanup});
+const detached = process.argv[3] === 'true';
+const subprocess = execa('node', ['./fixtures/forever'], {cleanup, detached});
 process.send(subprocess.pid);

fixtures/sub-process-exit

@@ -0,0 +1,7 @@
+#!/usr/bin/env node
+'use strict';
+const execa = require('..');
+
+const cleanup = process.argv[2] === 'true';
+const detached = process.argv[3] === 'true';
+execa('node', ['./fixtures/noop'], {cleanup, detached});

index.d.ts

@@ -101,7 +101,9 @@ declare namespace execa {
 		readonly reject?: boolean;
 
 		/**
-		Keep track of the spawned process and `kill` it when the parent process exits.
+		Kill the spawned process when the parent process exits unless either:
+			- the spawned process is [`detached`](https://nodejs.org/api/child_process.html#child_process_options_detached)
+			- the parent process is terminated abruptly, for example, with `SIGKILL` as opposed to `SIGTERM` or a normal exit
 
 		@default true
 		*/

index.js

@@ -93,11 +93,6 @@ function handleArgs(command, args, options = {}) {
 
 	options.stdio = stdio(options);
 
-	if (options.detached) {
-		// #115
-		options.cleanup = false;
-	}
-
 	if (process.platform === 'win32' && path.basename(command, '.exe') === 'cmd') {
 		// #116
 		args.unshift('/q');
@@ -264,8 +259,9 @@ const execa = (command, args, options) => {
 		return Promise.reject(error);
 	}
 
+	// #115
 	let removeExitHandler;
-	if (parsed.options.cleanup) {
+	if (parsed.options.cleanup && !parsed.options.detached) {
 		removeExitHandler = onExit(() => {
 			spawned.kill();
 		});

readme.md

@@ -277,7 +277,9 @@ Setting this to `false` resolves the promise with the error instead of rejecting
 Type: `boolean`<br>
 Default: `true`
 
-Keep track of the spawned process and `kill` it when the parent process exits.
+Kill the spawned process when the parent process exits unless either:
+	- the spawned process is [`detached`](https://nodejs.org/api/child_process.html#child_process_options_detached)
+	- the parent process is terminated abruptly, for example, with `SIGKILL` as opposed to `SIGTERM` or a normal exit
 
 #### encoding
 

test.js

@@ -485,8 +485,19 @@ test(command, ' foo bar', 'foo', 'bar');
 test(command, ' baz quz', 'baz', 'quz');
 test(command, '');
 
-async function spawnAndKill(t, signal, cleanup, isKilled) {
-	const subprocess = execa('sub-process', [cleanup], {stdio: ['ignore', 'ignore', 'ignore', 'ipc']});
+// When child process exits before parent process
+async function spawnAndExit(t, cleanup, detached) {
+	await t.notThrowsAsync(execa('sub-process-exit', [cleanup, detached]));
+}
+
+test('spawnAndExit', spawnAndExit, false, false);
+test('spawnAndExit cleanup', spawnAndExit, true, false);
+test('spawnAndExit detached', spawnAndExit, false, true);
+test('spawnAndExit cleanup detached', spawnAndExit, true, true);
+
+// When parent process exits before child process
+async function spawnAndKill(t, signal, cleanup, detached, isKilled) {
+	const subprocess = execa('sub-process', [cleanup, detached], {stdio: ['ignore', 'ignore', 'ignore', 'ipc']});
 
 	const pid = await pEvent(subprocess, 'message');
 	t.true(Number.isInteger(pid));
@@ -498,6 +509,10 @@ async function spawnAndKill(t, signal, cleanup, isKilled) {
 
 	t.false(isRunning(subprocess.pid));
 	t.is(isRunning(pid), !isKilled);
+
+	if (!isKilled) {
+		process.kill(pid, 'SIGKILL');
+	}
 }
 
 // Without `options.cleanup`:
@@ -507,10 +522,14 @@ async function spawnAndKill(t, signal, cleanup, isKilled) {
 // With `options.cleanup`, subprocesses are always killed
 //   - `options.cleanup` with SIGKILL is a noop, since it cannot be handled
 const exitIfWindows = process.platform === 'win32';
-test('cleanup true - SIGTERM', spawnAndKill, 'SIGTERM', 'true', true);
-test('cleanup false - SIGTERM', spawnAndKill, 'SIGTERM', 'false', exitIfWindows);
-test('cleanup true - SIGKILL', spawnAndKill, 'SIGKILL', 'true', exitIfWindows);
-test('cleanup false - SIGKILL', spawnAndKill, 'SIGKILL', 'false', exitIfWindows);
+test('spawnAndKill SIGTERM', spawnAndKill, 'SIGTERM', false, false, exitIfWindows);
+test('spawnAndKill SIGKILL', spawnAndKill, 'SIGKILL', false, false, exitIfWindows);
+test('spawnAndKill cleanup SIGTERM', spawnAndKill, 'SIGTERM', true, false, true);
+test('spawnAndKill cleanup SIGKILL', spawnAndKill, 'SIGKILL', true, false, exitIfWindows);
+test('spawnAndKill detached SIGTERM', spawnAndKill, 'SIGTERM', false, true, false);
+test('spawnAndKill detached SIGKILL', spawnAndKill, 'SIGKILL', false, true, false);
+test('spawnAndKill cleanup detached SIGTERM', spawnAndKill, 'SIGTERM', true, true, false);
+test('spawnAndKill cleanup detached SIGKILL', spawnAndKill, 'SIGKILL', true, true, false);
 
 test('execa.shell() supports the `shell` option', async t => {
 	const {stdout} = await execa.shell('node fixtures/noop foo', {