[6.x] Fix last_modified option in SetCacheHeader

src/Illuminate/Http/Middleware/SetCacheHeaders.php

@@ -3,6 +3,7 @@
 namespace Illuminate\Http\Middleware;
 
 use Closure;
+use Illuminate\Support\Carbon;
 
 class SetCacheHeaders
 {
@@ -32,6 +33,14 @@ public function handle($request, Closure $next, $options = [])
             $options['etag'] = md5($response->getContent());
         }
 
+        if (isset($options['last_modified'])) {
+            if (is_numeric($options['last_modified'])) {
+                $options['last_modified'] = Carbon::createFromTimestamp($options['last_modified']);
+            } else {
+                $options['last_modified'] = Carbon::parse($options['last_modified']);
+            }
+        }
+
         $response->setCache($options);
         $response->isNotModified($request);
 

tests/Http/Middleware/CacheTest.php

@@ -5,6 +5,7 @@
 use Illuminate\Http\Middleware\SetCacheHeaders as Cache;
 use Illuminate\Http\Request;
 use Illuminate\Http\Response;
+use Illuminate\Support\Carbon;
 use InvalidArgumentException;
 use PHPUnit\Framework\TestCase;
 
@@ -82,4 +83,25 @@ public function testInvalidOption()
             return new Response('some content');
         }, 'invalid');
     }
+
+    public function testLastModifiedUnixTime()
+    {
+        $time = time();
+
+        $response = (new Cache)->handle(new Request, function () {
+            return new Response('some content');
+        }, "last_modified=$time");
+
+        $this->assertSame($time, $response->getLastModified()->getTimestamp());
+    }
+
+    public function testLastModifiedStringDate()
+    {
+        $birthdate = '1973-04-09 10:10:10';
+        $response = (new Cache)->handle(new Request, function () {
+            return new Response('some content');
+        }, "last_modified=$birthdate");
+
+        $this->assertSame(Carbon::parse($birthdate)->timestamp, $response->getLastModified()->getTimestamp());
+    }
 }