From e36a60693b584779b93ebe1ca9efde56f0a3dd2a Mon Sep 17 00:00:00 2001
From: Phil DeJarnett <phil@overzealous.com>
Date: Wed, 19 Nov 2014 16:34:01 -0500
Subject: [PATCH] Cloned input arrays to prevent modification of passed-in
 values, found by @Peter-Donner.  Fixes #18

---
 index.js     | 5 ++++-
 test/main.js | 8 ++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/index.js b/index.js
index a46d513..c5e7fb0 100644
--- a/index.js
+++ b/index.js
@@ -34,7 +34,10 @@ function verifyTaskSets(gulp, taskSets, skipArrays) {
 }
 
 function runSequence(gulp) {
-	var taskSets = Array.prototype.slice.call(arguments, 1),
+	// Slice and dice the input to prevent modification of parallel arrays.
+	var taskSets = Array.prototype.slice.call(arguments, 1).map(function(task) {
+			return Array.isArray(task) ? task.slice() : task;
+		}),
 		callBack = typeof taskSets[taskSets.length-1] === 'function' ? taskSets.pop() : false,
 		currentTaskSet,
 
diff --git a/test/main.js b/test/main.js
index b91f5d8..b238dcc 100644
--- a/test/main.js
+++ b/test/main.js
@@ -74,6 +74,14 @@ describe('runSequence', function() {
 		})
 	});
 
+	describe('Input Array Handling', function() {
+		it('should not modify passed-in parallel task arrays', function() {
+			var taskArray = ['task1', 'task2'];
+			runSequence(taskArray);
+			taskArray.should.eql(['task1', 'task2']);
+		});
+	});
+
 	describe('Asynchronous Tasks', function() {
 		it('should run a single task', function() {
 			task1.shouldPause = true;