Handle headers that occur more than once

As outlined in RFC 2616 Sec 4.2 paragraph 5
fixes #50

composer.json

@@ -4,7 +4,7 @@
     "homepage": "http://github.com/nategood/httpful",
     "license": "MIT",
     "keywords": ["http", "curl", "rest", "restful", "api", "requests"],
-    "version": "0.1.6",
+    "version": "0.1.7",
     "authors": [
         {
             "name": "Nate Good",

src/Httpful/Httpful.php

@@ -3,7 +3,7 @@
 namespace Httpful;
 
 class Httpful {
-    const VERSION = '0.1.5';
+    const VERSION = '0.1.7';
 
     private static $mimeRegistrar = array();
     private static $default = null;

src/Httpful/Response.php

@@ -115,7 +115,18 @@ public function _parseHeaders($headers)
         $parse_headers = array();
         for ($i = 1; $i < count($headers); $i++) {
             list($key, $raw_value) = explode(':', $headers[$i], 2);
-            $parse_headers[trim($key)] = trim($raw_value);
+            $key = trim($key);
+            $value = trim($raw_value);
+            if (array_key_exists($key, $parse_headers)) {
+                // See HTTP RFC Sec 4.2 Paragraph 5
+                // http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2
+                // If a header appears more than once, it must also be able to
+                // be represented as a single header with a comma-separated
+                // list of values.  We transform accordingly.
+                $parse_headers[$key] .= ',' . $value;
+            } else {
+                $parse_headers[$key] = $value;
+            }
         }
         return $parse_headers;
     }

tests/Httpful/HttpfulTest.php

@@ -51,7 +51,13 @@ class HttpfulTest extends \PHPUnit_Framework_TestCase
 Connection: keep-alive
 Transfer-Encoding: chunked\r\n";
     const SAMPLE_VENDOR_TYPE = "application/vnd.nategood.message+xml";
-
+    const SAMPLE_MULTI_HEADER =
+"HTTP/1.1 200 OK
+Content-Type: application/json
+Connection: keep-alive
+Transfer-Encoding: chunked
+X-My-Header:Value1
+X-My-Header:Value2\r\n";
     function testInit()
     {
       $r = Request::init();
@@ -338,6 +344,14 @@ function test_parseHeaders()
         $this->assertArrayHasKey('Connection', $parse_headers);
     }
 
+    function testMultiHeaders()
+    {
+        $req = Request::init();
+        $response = new Response(self::SAMPLE_JSON_RESPONSE, self::SAMPLE_MULTI_HEADER, $req);
+        $parse_headers = $response->_parseHeaders(self::SAMPLE_MULTI_HEADER);
+        $this->assertEquals('Value1,Value2', $parse_headers['X-My-Header']);
+    }
+
     function testDetectContentType()
     {
         $req = Request::init();