add test unit headers_to_array with multiple same headers

t/12_response/09_headers_to_array.t

@@ -0,0 +1,22 @@
+package main;
+use strict;
+use warnings;
+use Test::More tests => 1, import => ['!pass'];
+
+{
+
+    use Dancer;
+    get '/' => sub {
+        push_header A => 1;
+        push_header A => 2;
+        push_header B => 3;
+    };
+
+}
+
+use Dancer::Test;
+
+response_headers_are_deeply [GET => '/'],
+  [ 'Content-Type' => 'text/html', 'A' => 1, 'A' => 2, 'B' => 3];
+
+1;