bug #19397 [2.7] [HttpFoundation] HttpCache refresh stale responses containing an ETag (maennchen)

This PR was merged into the 2.7 branch.

Discussion
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[2.7] [HttpFoundation] HttpCache refresh stale responses containing an ETag

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  |no
| BC breaks?    |no
| Deprecations? |no
| Tests pass?   | yes
| Fixed tickets | #19390, #6746
| License       | MIT
| Doc PR        |

This PR is the replacement of #19391, which points at the wrong branch.

Commits
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96df6b9 [HttpFoundation] HttpCache refresh stale responses containing an ETag

Author: nicolas-grekas

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

@@ -600,6 +600,9 @@ protected function lock(Request $request, Response $entry)
      */
     protected function store(Request $request, Response $response)
     {
+        if (!$response->headers->has('Date')) {
+            $response->setDate(\DateTime::createFromFormat('U', time()));
+        }
         try {
             $this->store->write($request, $response);
 

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

@@ -181,6 +181,31 @@ public function testRespondsWith304OnlyIfIfNoneMatchAndIfModifiedSinceBothMatch(
         $this->assertEquals(304, $this->response->getStatusCode());
     }
 
+    public function testIncrementsMaxAgeWhenNoDateIsSpecifiedEventWhenUsingETag()
+    {
+        $this->setNextResponse(
+            200,
+            array(
+                'ETag' => '1234',
+                'Cache-Control' => 'public, s-maxage=60',
+            )
+        );
+
+        $this->request('GET', '/');
+        $this->assertHttpKernelIsCalled();
+        $this->assertEquals(200, $this->response->getStatusCode());
+        $this->assertTraceContains('miss');
+        $this->assertTraceContains('store');
+
+        sleep(2);
+
+        $this->request('GET', '/');
+        $this->assertHttpKernelIsNotCalled();
+        $this->assertEquals(200, $this->response->getStatusCode());
+        $this->assertTraceContains('fresh');
+        $this->assertEquals(2, $this->response->headers->get('Age'));
+    }
+
     public function testValidatesPrivateResponsesCachedOnTheClient()
     {
         $this->setNextResponse(200, array(), '', function ($request, $response) {