Update

Author: odan

Slim/Routing/PipelineOrder.php

@@ -27,17 +27,14 @@ final class PipelineRunner implements RequestHandlerInterface
 {
     private ContainerResolverInterface $resolver;
 
-    private PipelineOrder $order;
-
     /**
      * @var array<int, mixed>
      */
     private array $pipeline = [];
 
-    public function __construct(ContainerResolverInterface $resolver, PipelineOrder $order = PipelineOrder::FIFO)
+    public function __construct(ContainerResolverInterface $resolver)
     {
         $this->resolver = $resolver;
-        $this->order = $order;
     }
 
     /**
@@ -51,26 +48,18 @@ public function withPipeline(array $pipeline): self
         return $clone;
     }
 
-    public function withOrder(PipelineOrder $order): self
-    {
-        $clone = clone $this;
-        $clone->order = $order;
-
-        return $clone;
-    }
-
     public function handle(ServerRequestInterface $request): ResponseInterface
     {
-        $entry = $this->order === PipelineOrder::FIFO
-            ? array_shift($this->pipeline)
-            : array_pop($this->pipeline);
+        $entry = current($this->pipeline);
 
         if (!$entry) {
             throw new RuntimeException('The middleware pipeline is empty.');
         }
 
         $entry = $this->resolver->resolve($entry);
 
+        next($this->pipeline);
+
         if ($entry instanceof MiddlewareInterface) {
             return $entry->process($request, $this);
         }

Slim/Routing/PipelineRunner.php

@@ -14,7 +14,6 @@
 use Psr\Http\Server\RequestHandlerInterface;
 use RuntimeException;
 use Slim\Factory\AppFactory;
-use Slim\Routing\PipelineOrder;
 use Slim\Routing\PipelineRunner;
 use stdClass;
 
@@ -191,58 +190,4 @@ public function testHandleWithInvalidMiddlewareStringThrowsException(): void
 
         $runner->handle($request);
     }
-
-    public function testHandleExecutesPipelineInLifoOrder(): void
-    {
-        $app = AppFactory::create();
-        $container = $app->getContainer();
-
-        $request = $container
-            ->get(ServerRequestFactoryInterface::class)
-            ->createServerRequest('GET', '/');
-
-        $responseFactory = $container->get(ResponseFactoryInterface::class);
-
-        // This middleware will be executed LAST in LIFO mode (because it was added first).
-        $first = new class implements MiddlewareInterface {
-            public function process(
-                ServerRequestInterface $request,
-                RequestHandlerInterface $handler,
-            ): ResponseInterface {
-                $response = $handler->handle($request);
-                return $response->withHeader('X-Order', 'First');
-            }
-        };
-
-        // This middleware will be executed FIRST in LIFO mode.
-        $second = new class implements MiddlewareInterface {
-            public function process(
-                ServerRequestInterface $request,
-                RequestHandlerInterface $handler,
-            ): ResponseInterface {
-                $response = $handler->handle($request);
-                return $response->withHeader('X-Order', 'Second');
-            }
-        };
-
-        // Final handler that produces a basic response
-        $finalHandler = fn() => $responseFactory->createResponse();
-
-        $runner = $container
-            ->get(PipelineRunner::class)
-            ->withOrder(PipelineOrder::LIFO)
-            ->withPipeline(
-                [
-                    $finalHandler,  // end
-                    $second,        // ^ second
-                    $first,         // ^ start
-                ],
-            );
-
-        $response = $runner->handle($request);
-
-        $this->assertSame('First', $response->getHeaderLine('X-Order'));
-    }
-
-
 }