Add is array test

lib/Twig/Extension/Core.php

@@ -202,6 +202,7 @@ class Twig_Extension_Core extends Twig_Extension
             'divisibleby' => new Twig_Test_Node('Twig_Node_Expression_Test_Divisibleby'),
             'constant'    => new Twig_Test_Node('Twig_Node_Expression_Test_Constant'),
             'empty'       => new Twig_Test_Function('twig_test_empty'),
+            'array'       => new Twig_Test_Function('is_array'),
         );
     }
 

test/Twig/Tests/Fixtures/tests/is_array.test

@@ -0,0 +1,16 @@
+--TEST--
+"is_array" test
+--TEMPLATE--
+{{ foo is array ? 'ok' : 'ko' }}
+{{ obj is array ? 'ok' : 'ko' }}
+{{ val is array ? 'ok' : 'ko' }}
+--DATA--
+return array(
+    'foo' => array(),
+    'obj' => new stdClass(),
+    'val' => 'test',
+);
+--EXPECT--
+ok
+ko
+ko