Append to Link header if it is already present (#19)

src/Middleware/AddHttp2ServerPush.php

@@ -9,7 +9,6 @@
 
 class AddHttp2ServerPush
 {
-
     /**
      * The DomCrawler instance.
      *
@@ -116,7 +115,6 @@ private function buildLinkHeaderString($url)
         });
 
         return is_null($type) ? null : "<{$url}>; rel=preload; as={$type}";
-
     }
 
     /**
@@ -128,7 +126,10 @@ private function buildLinkHeaderString($url)
      */
     private function addLinkHeader(Response $response, $link)
     {
+        if ($response->headers->get('Link')) {
+            $link = $response->headers->get('Link') . ',' . $link;
+        }
+
         $response->header('Link', $link);
     }
-
 }

tests/AddHttp2ServerPushTest.php

@@ -104,6 +104,24 @@ public function it_will_return_limit_count_of_links()
         $this->assertCount($limit, explode(",", $response->headers->get('link')));
     }
 
+    /** @test */
+    public function it_will_append_to_header_if_already_present()
+    {
+        $request = new Request();
+
+        $next = $this->getNext('pageWithCss');
+
+        $response = $this->middleware->handle($request, function ($request) use ($next) {
+            $response = $next($request);
+            $response->headers->set('Link', '<https://example.com/en>; rel="alternate"; hreflang="en"');
+            return $response;
+        });
+
+        $this->assertTrue($this->isServerPushResponse($response));
+        $this->assertStringStartsWith('<https://example.com/en>; rel="alternate"; hreflang="en",', $response->headers->get('link'));
+        $this->assertStringEndsWith("as=style", $response->headers->get('link'));
+    }
+
     /**
      * @param string $pageName
      *
@@ -116,7 +134,6 @@ protected function getNext($pageName)
         $response = (new \Illuminate\Http\Response($html));
 
         return function ($request) use ($response) {
-
             return $response;
         };
     }