Merge branch '2.8' into 3.2

* 2.8:
  HttpCache: New test for revalidating responses with an expired TTL
  [Serializer] [XML] Ignore Process Instruction

src/Symfony/Component/HttpKernel/Tests/HttpCache/HttpCacheTest.php

@@ -849,6 +849,42 @@ class HttpCacheTest extends HttpCacheTestCase
         $this->assertTraceNotContains('miss');
     }
 
+    public function testServesResponseWhileFreshAndRevalidatesWithLastModifiedInformation()
+    {
+        $time = \DateTime::createFromFormat('U', time());
+
+        $this->setNextResponse(200, array(), 'Hello World', function (Request $request, Response $response) use ($time) {
+            $response->setSharedMaxAge(10);
+            $response->headers->set('Last-Modified', $time->format(DATE_RFC2822));
+        });
+
+        // prime the cache
+        $this->request('GET', '/');
+
+        // next request before s-maxage has expired: Serve from cache
+        // without hitting the backend
+        $this->request('GET', '/');
+        $this->assertHttpKernelIsNotCalled();
+        $this->assertEquals(200, $this->response->getStatusCode());
+        $this->assertEquals('Hello World', $this->response->getContent());
+        $this->assertTraceContains('fresh');
+
+        sleep(15); // expire the cache
+
+        $that = $this;
+
+        $this->setNextResponse(304, array(), '', function (Request $request, Response $response) use ($time, $that) {
+            $that->assertEquals($time->format(DATE_RFC2822), $request->headers->get('IF_MODIFIED_SINCE'));
+        });
+
+        $this->request('GET', '/');
+        $this->assertHttpKernelIsCalled();
+        $this->assertEquals(200, $this->response->getStatusCode());
+        $this->assertEquals('Hello World', $this->response->getContent());
+        $this->assertTraceContains('stale');
+        $this->assertTraceContains('valid');
+    }
+
     public function testReplacesCachedResponsesWhenValidationResultsInNon304Response()
     {
         $time = \DateTime::createFromFormat('U', time());

src/Symfony/Component/Serializer/Encoder/XmlEncoder.php

@@ -95,14 +95,16 @@ class XmlEncoder extends SerializerAwareEncoder implements EncoderInterface, Dec
             throw new UnexpectedValueException($error->message);
         }
 
+        $rootNode = null;
         foreach ($dom->childNodes as $child) {
             if ($child->nodeType === XML_DOCUMENT_TYPE_NODE) {
                 throw new UnexpectedValueException('Document types are not allowed.');
             }
+            if (!$rootNode && $child->nodeType !== XML_PI_NODE) {
+                $rootNode = $child;
+            }
         }
 
-        $rootNode = $dom->firstChild;
-
         // todo: throw an exception if the root node name is not correctly configured (bc)
 
         if ($rootNode->hasChildNodes()) {
@@ -332,6 +334,10 @@ class XmlEncoder extends SerializerAwareEncoder implements EncoderInterface, Dec
         $value = array();
 
         foreach ($node->childNodes as $subnode) {
+            if ($subnode->nodeType === XML_PI_NODE) {
+                continue;
+            }
+
             $val = $this->parseXml($subnode);
 
             if ('item' === $subnode->nodeName && isset($val['@key'])) {

src/Symfony/Component/Serializer/Tests/Encoder/XmlEncoderTest.php

@@ -370,6 +370,44 @@ XML;
         $this->assertEquals($expected, $this->encoder->decode($source, 'xml'));
     }
 
+    public function testDecodeXMLWithProcessInstruction()
+    {
+        $source = <<<'XML'
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/xsl" href="/xsl/xmlverbatimwrapper.xsl"?>
+    <?display table-view?>
+    <?sort alpha-ascending?>
+    <response>
+        <foo>foo</foo>
+        <?textinfo whitespace is allowed ?>
+        <bar>a</bar>
+        <bar>b</bar>
+        <baz>
+            <key>val</key>
+            <key2>val</key2>
+            <item key="A B">bar</item>
+            <item>
+                <title>title1</title>
+            </item>
+            <?item ignore-title ?>
+            <item>
+                <title>title2</title>
+            </item>
+            <Barry>
+                <FooBar id="1">
+                    <Baz>Ed</Baz>
+                </FooBar>
+            </Barry>
+        </baz>
+        <qux>1</qux>
+    </response>
+    <?instruction <value> ?>
+XML;
+        $obj = $this->getObject();
+
+        $this->assertEquals(get_object_vars($obj), $this->encoder->decode($source, 'xml'));
+    }
+
     public function testDecodeIgnoreWhiteSpace()
     {
         $source = <<<'XML'