Add fork method - fixes #65

fixtures/ipc-process

@@ -0,0 +1,9 @@
+#!/usr/bin/env node
+'use strict';
+process.on('message', m => {
+	if (m === 'ping') {
+		process.send('pong');
+	} else {
+		process.send('rainbow');
+	}
+});

index.js

@@ -278,6 +278,20 @@ module.exports = (cmd, args, opts) => {
 	return spawned;
 };
 
+module.exports.fork = function (cmd, args, opts) {
+	opts = Object.assign({
+		stdio: 'ipc'
+	}, opts);
+
+	if (opts.stdio === 'ipc') {
+		opts.stdio = [0, 1, 2, 'ipc'];
+	}
+
+	// TODO throw `new TypeError('Forked processes must have an IPC channel')` if no IPC channel is provided
+	// TODO throw `new Error('Child process can have only one IPC pipe')` when multiple IPC channels are provided
+	return module.exports(cmd, args, opts);
+};
+
 module.exports.stdout = function () {
 	// TODO: set `stderr: 'ignore'` when that option is implemented
 	return module.exports.apply(null, arguments).then(x => x.stdout);

test.js

@@ -109,6 +109,17 @@ test('execa.shellSync()', t => {
 	t.is(stdout, 'foo');
 });
 
+test.cb('execa.fork()', t => {
+	const cp = m.fork('fixtures/ipc-process');
+
+	cp.on('message', m => {
+		t.is(m, 'pong');
+		t.end();
+	});
+
+	cp.send('ping');
+});
+
 test('stripEof option', async t => {
 	const {stdout} = await m('noop', ['foo'], {stripEof: false});
 	t.is(stdout, 'foo\n');