[Fix] quote: preserve empty strings

Fixes #18

Author: ljharb

quote.js

@@ -2,6 +2,9 @@
 
 module.exports = function quote(xs) {
 	return xs.map(function (s) {
+		if (s === '') {
+			return '\'\'';
+		}
 		if (s && typeof s === 'object') {
 			return s.op.replace(/(.)/g, '\\$1');
 		}

test/parse.js

@@ -38,5 +38,7 @@ test('parse shell commands', function (t) {
 	t.deepEqual(parse('# abc  def  ghi'), [{ comment: ' abc  def  ghi' }], 'start-of-line comment content is unparsed');
 	t.deepEqual(parse('xyz # abc  def  ghi'), ['xyz', { comment: ' abc  def  ghi' }], 'comment content is unparsed');
 
+	t.deepEqual(parse('-x "" -y'), ['-x', '', '-y'], 'empty string is preserved');
+
 	t.end();
 });

test/quote.js

@@ -48,3 +48,9 @@ test("chars for windows paths don't break out", function (t) {
 	t.equal(quote([x]), '\\`\\:\\\\a\\\\b');
 	t.end();
 });
+
+test('empty strings', function (t) {
+	t.equal(quote(['-x', '', 'y']), '-x \'\' y');
+
+	t.end();
+});