From 4ffed0451258ec1b1a95e911ee84a6a426cc5321 Mon Sep 17 00:00:00 2001
From: Brian Maissy <brian.maissy@gmail.com>
Date: Sun, 3 Mar 2013 00:50:47 +0200
Subject: calling waterfall with a non-array first argument results in an error

---
 lib/async.js       | 4 ++++
 test/test-async.js | 7 +++++++
 2 files changed, 11 insertions(+)

diff --git a/lib/async.js b/lib/async.js
index a805447..2ec1934 100755
--- a/lib/async.js
+++ b/lib/async.js
@@ -467,6 +467,10 @@
 
     async.waterfall = function (tasks, callback) {
         callback = callback || function () {};
+        if (tasks.constructor !== Array) {
+          var err = new Error('First argument to waterfall must be an array of functions');
+          return callback(err);
+        }
         if (!tasks.length) {
             return callback();
         }
diff --git a/test/test-async.js b/test/test-async.js
index 1caf1bc..62e0643 100755
--- a/test/test-async.js
+++ b/test/test-async.js
@@ -360,6 +360,13 @@ exports['waterfall empty array'] = function(test){
     });
 };
 
+exports['waterfall non-array'] = function(test){
+    async.waterfall({}, function(err){
+        test.equals(err.message, 'First argument to waterfall must be an array of functions');
+        test.done();
+    });
+};
+
 exports['waterfall no callback'] = function(test){
     async.waterfall([
         function(callback){callback();},
-- 
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