[8.x] Allows Stringable objects as middleware.

src/Illuminate/Routing/PendingResourceRegistration.php

@@ -149,6 +149,14 @@ public function parameter($previous, $new)
      */
     public function middleware($middleware)
     {
+        if (! is_string($middleware)) {
+            $middleware = Arr::wrap($middleware);
+
+            foreach ($middleware as $key => $value) {
+                $middleware[$key] = (string) $value;
+            }
+        }
+
         $this->options['middleware'] = $middleware;
 
         return $this;

src/Illuminate/Routing/RouteRegistrar.php

@@ -93,6 +93,14 @@ public function attribute($key, $value)
             throw new InvalidArgumentException("Attribute [{$key}] does not exist.");
         }
 
+        if ($key === 'middleware' && ! is_string($value)) {
+            $value = Arr::wrap($value);
+
+            foreach ($value as $index => $middleware) {
+                $value[$index] = (string) $middleware;
+            }
+        }
+
         $this->attributes[Arr::get($this->aliases, $key, $key)] = $value;
 
         return $this;

tests/Routing/RouteRegistrarTest.php

@@ -9,6 +9,7 @@
 use Illuminate\Routing\Router;
 use Mockery as m;
 use PHPUnit\Framework\TestCase;
+use Stringable;
 
 class RouteRegistrarTest extends TestCase
 {
@@ -60,6 +61,42 @@ public function testMiddlewareFluentRegistration()
         $this->assertEquals(['seven'], $this->getRoute()->middleware());
     }
 
+    public function testMiddlewareAsStringableObject()
+    {
+        $one = new class implements Stringable
+        {
+            public function __toString()
+            {
+                return 'one';
+            }
+        };
+
+        $this->router->middleware($one)->get('users', function () {
+            return 'all-users';
+        });
+
+        $this->seeResponse('all-users', Request::create('users', 'GET'));
+        $this->assertSame(['one'], $this->getRoute()->middleware());
+    }
+
+    public function testMiddlewareAsArrayWithStringables()
+    {
+        $one = new class implements Stringable
+        {
+            public function __toString()
+            {
+                return 'one';
+            }
+        };
+
+        $this->router->middleware([$one, 'two'])->get('users', function () {
+            return 'all-users';
+        });
+
+        $this->seeResponse('all-users', Request::create('users', 'GET'));
+        $this->assertSame(['one', 'two'], $this->getRoute()->middleware());
+    }
+
     public function testWithoutMiddlewareRegistration()
     {
         $this->router->middleware(['one', 'two'])->get('users', function () {
@@ -606,6 +643,27 @@ public function testResourceWithoutMiddlewareRegistration()
         $this->assertEquals(['one'], $this->getRoute()->excludedMiddleware());
     }
 
+    public function testResourceWithMiddlewareAsStringable()
+    {
+        $one = new class implements Stringable
+        {
+            public function __toString()
+            {
+                return 'one';
+            }
+        };
+
+        $this->router->resource('users', RouteRegistrarControllerStub::class)
+                     ->only('index')
+                     ->middleware([$one, 'two'])
+                     ->withoutMiddleware('one');
+
+        $this->seeResponse('controller', Request::create('users', 'GET'));
+
+        $this->assertEquals(['one', 'two'], $this->getRoute()->middleware());
+        $this->assertEquals(['one'], $this->getRoute()->excludedMiddleware());
+    }
+
     public function testResourceWheres()
     {
         $wheres = [