validate argument length

index.js

@@ -1,7 +1,3 @@
-/*!
- * glob-observable | MIT (c) Shinnosuke Watanabe
- * https://github.com/shinnn/glob-observable
-*/
 'use strict';
 
 const {inspect} = require('util');
@@ -13,14 +9,27 @@ const Glob = require('glob').Glob;
 const {makeAbs} = require('glob/common.js');
 const Observable = require('zen-observable');
 
-module.exports = function globObservable(pattern, options) {
+module.exports = function globObservable(...args) {
 	return new Observable(observer => {
+		const argLen = args.length;
+
+		if (argLen !== 1 && argLen !== 2) {
+			throw new RangeError(`Expected 1 or 2 arguments (<string>[, <Object>]), but got ${
+				argLen === 0 ? 'no' : argLen
+			} arguments.`);
+		}
+
+		const [pattern] = args;
+
 		if (typeof pattern !== 'string') {
 			throw new TypeError(`Expected a glob pattern string, but got ${inspect(pattern)}.`);
 		}
 
-		assertValidGlobOpts(options);
-		options = options || {};
+		if (argLen === 2) {
+			assertValidGlobOpts(args[1]);
+		}
+
+		const options = args[1] || {};
 
 		const realpath = options.realpath;
 		const unique = options.nounique !== true;

test.js

@@ -15,7 +15,7 @@ const dummyFileStat = new Stats(1000000, 33188, 1, 501, 20, 0, 4096, 500000, 1,
 const dummyFilePath = slash(resolve('__actually_this_file_does_not_exist__'));
 
 test('globObservable()', async t => {
-	t.plan(13);
+	t.plan(15);
 
 	await rmfr('tmp');
 	await Promise.all([
@@ -186,4 +186,28 @@ test('globObservable()', async t => {
 		},
 		complete: unexpectedComplete
 	});
+
+	globObservable()
+	.subscribe({
+		error({message}) {
+			t.equal(
+				message,
+				'Expected 1 or 2 arguments (<string>[, <Object>]), but got no arguments.',
+				'should fail when it takes no arguments.'
+			);
+		},
+		complete: unexpectedComplete
+	});
+
+	globObservable('', {}, '')
+	.subscribe({
+		error({message}) {
+			t.equal(
+				message,
+				'Expected 1 or 2 arguments (<string>[, <Object>]), but got 3 arguments.',
+				'should fail when it takes too many arguments.'
+			);
+		},
+		complete: unexpectedComplete
+	});
 });