Fix call to undefined method when download file

src/SecureHeadersMiddleware.php

@@ -5,6 +5,7 @@
 use Closure;
 use Illuminate\Http\Request;
 use Illuminate\Http\Response;
+use Symfony\Component\HttpFoundation\BinaryFileResponse;
 
 class SecureHeadersMiddleware
 {
@@ -20,6 +21,11 @@ public function handle(Request $request, Closure $next)
     {
         $response = $next($request);
 
+        // when response is BinaryFileResponse, we should not add headers
+        if ($response instanceof BinaryFileResponse) {
+            return $response;
+        }
+
         $headers = (new SecureHeaders(config('secure-headers', [])))->headers();
 
         foreach ($headers as $key => $value) {

tests/MiddlewareTest.php

@@ -30,9 +30,25 @@ protected function getEnvironmentSetUp($app)
 
     public function test_middleware()
     {
+        $this->app['router']->get('/', function () {
+            return 'Hello World!';
+        });
+
         $response = $this->get('/');
 
         $response->assertHeader('x-frame-options');
         $response->assertHeader('content-security-policy');
     }
+
+    public function test_binary_response()
+    {
+        $this->app['router']->get('/', function () {
+            return response()->download(__DIR__.'/../README.md');
+        });
+
+        $response = $this->get('/');
+
+        $this->assertFalse($response->headers->has('x-content-type-options'));
+        $this->assertFalse($response->headers->has('content-security-policy'));
+    }
 }