[Fix] opt.string works with multiple aliases

Fixes #9.

index.js

@@ -61,7 +61,9 @@ module.exports = function (args, opts) {
 	[].concat(opts.string).filter(Boolean).forEach(function (key) {
 		flags.strings[key] = true;
 		if (aliases[key]) {
-			flags.strings[aliases[key]] = true;
+			[].concat(aliases[key]).forEach(function (k) {
+				flags.strings[k] = true;
+			});
 		}
 	});
 

package.json

@@ -20,7 +20,7 @@
 		"prepublish": "not-in-publish || npm run prepublishOnly",
 		"lint": "eslint --ext=js,mjs .",
 		"pretest": "npm run lint",
-		"tests-only": "nyc tape test/*.js",
+		"tests-only": "nyc tape 'test/**/*.js'",
 		"test": "npm run tests-only",
 		"posttest": "aud --production",
 		"version": "auto-changelog && git add CHANGELOG.md",

test/parse.js

@@ -142,6 +142,17 @@ test('string and alias', function (t) {
 	t.equal(typeof y.str, 'string');
 	t.equal(y.s, '000123');
 	t.equal(typeof y.s, 'string');
+
+	var z = parse(['-s123'], {
+		alias: { str: ['s', 'S'] },
+		string: ['str'],
+	});
+
+	t.deepEqual(
+		z,
+		{ _: [], s: '123', S: '123', str: '123' },
+		'opt.string works with multiple aliases'
+	);
 	t.end();
 });