diff --git a/.travis.yml b/.travis.yml
index feb3d49..2b0aa38 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,15 +1,23 @@
 language: php
 
+notifications:
+  email:
+    on_success: never
+
 php:
-  - 7.0
   - 7.1
   - 7.2
+  - 7.3
 
 matrix:
   include:
-    - php: 7.0
+    - php: 7.1
       env: dependencies=lowest
 
+cache:
+  directories:
+    - $HOME/.composer/cache
+
 sudo: false
 
 before_script:
diff --git a/composer.json b/composer.json
index e3d1df3..849b88e 100644
--- a/composer.json
+++ b/composer.json
@@ -14,12 +14,13 @@
         }
     },
     "require": {
-        "php": "~7.0",
+        "php": "~7.1",
         "php-di/php-di": "^6.0.0",
         "php-di/invoker": "^2.0.0",
-        "slim/slim": "^3.9.0"
+        "slim/slim": "^4.0.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~6.0"
+        "phpunit/phpunit": "~6.0",
+        "zendframework/zend-diactoros": "^2.1"
     }
 }
diff --git a/src/App.php b/src/App.php
deleted file mode 100644
index e1e0a56..0000000
--- a/src/App.php
+++ /dev/null
@@ -1,38 +0,0 @@
-<?php
-
-namespace DI\Bridge\Slim;
-
-use DI\ContainerBuilder;
-
-/**
- * Slim application configured with PHP-DI.
- *
- * As you can see, this class is very basic and is only useful to get started quickly.
- * You can also very well *not* use it and build the container manually.
- */
-class App extends \Slim\App
-{
-    public function __construct()
-    {
-        $containerBuilder = new ContainerBuilder;
-        $containerBuilder->addDefinitions(__DIR__ . '/config.php');
-        $this->configureContainer($containerBuilder);
-        $container = $containerBuilder->build();
-
-        parent::__construct($container);
-    }
-
-    /**
-     * Override this method to configure the container builder.
-     *
-     * For example, to load additional configuration files:
-     *
-     *     protected function configureContainer(ContainerBuilder $builder)
-     *     {
-     *         $builder->addDefinitions(__DIR__ . 'my-config-file.php');
-     *     }
-     */
-    protected function configureContainer(ContainerBuilder $builder)
-    {
-    }
-}
diff --git a/src/Bridge.php b/src/Bridge.php
new file mode 100644
index 0000000..c36a704
--- /dev/null
+++ b/src/Bridge.php
@@ -0,0 +1,55 @@
+<?php declare(strict_types=1);
+
+namespace DI\Bridge\Slim;
+
+use DI\Container;
+use Invoker\Invoker;
+use Invoker\ParameterResolver\AssociativeArrayResolver;
+use Invoker\ParameterResolver\Container\TypeHintContainerResolver;
+use Invoker\ParameterResolver\DefaultValueResolver;
+use Invoker\ParameterResolver\ResolverChain;
+use Psr\Container\ContainerInterface;
+use Slim\App;
+use Slim\Factory\AppFactory;
+use \Invoker\CallableResolver as InvokerCallableResolver;
+
+/**
+ * This factory creates a Slim application correctly configured with PHP-DI.
+ *
+ * To use this, replace `Slim\Factory\AppFactory::create()`
+ * with `DI\Bridge\Slim\Bridge::create()`.
+ */
+class Bridge
+{
+    public static function create(ContainerInterface $container = null): App
+    {
+        $container = $container ?: new Container;
+
+        AppFactory::setContainer($container);
+        $callableResolver = new InvokerCallableResolver($container);
+        AppFactory::setCallableResolver(new CallableResolver($callableResolver));
+
+        $app = AppFactory::create();
+
+        $controllerInvoker = self::createControllerInvoker($container);
+        $app->getRouteCollector()->setDefaultInvocationStrategy($controllerInvoker);
+
+        return $app;
+    }
+
+    private static function createControllerInvoker(ContainerInterface $container): ControllerInvoker
+    {
+        $resolvers = [
+            // Inject parameters by name first
+            new AssociativeArrayResolver(),
+            // Then inject services by type-hints for those that weren't resolved
+            new TypeHintContainerResolver($container),
+            // Then fall back on parameters default values for optional route parameters
+            new DefaultValueResolver(),
+        ];
+
+        $invoker = new Invoker(new ResolverChain($resolvers), $container);
+
+        return new ControllerInvoker($invoker);
+    }
+}
diff --git a/src/CallableResolver.php b/src/CallableResolver.php
index 40cc861..1321124 100644
--- a/src/CallableResolver.php
+++ b/src/CallableResolver.php
@@ -18,11 +18,10 @@ public function __construct(\Invoker\CallableResolver $callableResolver)
     {
         $this->callableResolver = $callableResolver;
     }
-
     /**
      * {@inheritdoc}
      */
-    public function resolve($toResolve)
+    public function resolve($toResolve): callable
     {
         return $this->callableResolver->resolve($toResolve);
     }
diff --git a/src/ControllerInvoker.php b/src/ControllerInvoker.php
index e16b8a4..8817b81 100644
--- a/src/ControllerInvoker.php
+++ b/src/ControllerInvoker.php
@@ -18,7 +18,6 @@ public function __construct(InvokerInterface $invoker)
     {
         $this->invoker = $invoker;
     }
-
     /**
      * Invoke a route callable.
      *
@@ -34,16 +33,14 @@ public function __invoke(
         ServerRequestInterface $request,
         ResponseInterface $response,
         array $routeArguments
-    ) {
+    ): ResponseInterface {
         // Inject the request and response by parameter name
         $parameters = [
             'request'  => $request,
             'response' => $response,
         ];
-
         // Inject the route arguments by name
         $parameters += $routeArguments;
-
         // Inject the attributes defined on the request
         $parameters += $request->getAttributes();
 
diff --git a/src/config.php b/src/config.php
deleted file mode 100644
index ea2bd61..0000000
--- a/src/config.php
+++ /dev/null
@@ -1,78 +0,0 @@
-<?php
-
-use function DI\autowire;
-use DI\Bridge\Slim\CallableResolver;
-use DI\Bridge\Slim\ControllerInvoker;
-use DI\Container;
-use function DI\create;
-use function DI\get;
-use Invoker\Invoker;
-use Invoker\ParameterResolver\AssociativeArrayResolver;
-use Invoker\ParameterResolver\Container\TypeHintContainerResolver;
-use Invoker\ParameterResolver\DefaultValueResolver;
-use Invoker\ParameterResolver\ResolverChain;
-use Psr\Container\ContainerInterface;
-use Slim\Http\Headers;
-use Slim\Http\Request;
-use Slim\Http\Response;
-
-return [
-
-    // Settings that can be customized by users
-    'settings.httpVersion' => '1.1',
-    'settings.responseChunkSize' => 4096,
-    'settings.outputBuffering' => 'append',
-    'settings.determineRouteBeforeAppMiddleware' => false,
-    'settings.displayErrorDetails' => false,
-    'settings.addContentLengthHeader' => true,
-    'settings.routerCacheFile' => false,
-
-    'settings' => [
-        'httpVersion' => get('settings.httpVersion'),
-        'responseChunkSize' => get('settings.responseChunkSize'),
-        'outputBuffering' => get('settings.outputBuffering'),
-        'determineRouteBeforeAppMiddleware' => get('settings.determineRouteBeforeAppMiddleware'),
-        'displayErrorDetails' => get('settings.displayErrorDetails'),
-        'addContentLengthHeader' => get('settings.addContentLengthHeader'),
-        'routerCacheFile' => get('settings.routerCacheFile'),
-    ],
-
-    // Default Slim services
-    'router' => create(Slim\Router::class)
-        ->method('setContainer', get(Container::class))
-        ->method('setCacheFile', get('settings.routerCacheFile')),
-    Slim\Router::class => get('router'),
-    'errorHandler' => create(Slim\Handlers\Error::class)
-        ->constructor(get('settings.displayErrorDetails')),
-    'phpErrorHandler' => create(Slim\Handlers\PhpError::class)
-        ->constructor(get('settings.displayErrorDetails')),
-    'notFoundHandler' => create(Slim\Handlers\NotFound::class),
-    'notAllowedHandler' => create(Slim\Handlers\NotAllowed::class),
-    'environment' => function () {
-        return new Slim\Http\Environment($_SERVER);
-    },
-    'request' => function (ContainerInterface $c) {
-        return Request::createFromEnvironment($c->get('environment'));
-    },
-    'response' => function (ContainerInterface $c) {
-        $headers = new Headers(['Content-Type' => 'text/html; charset=UTF-8']);
-        $response = new Response(200, $headers);
-        return $response->withProtocolVersion($c->get('settings')['httpVersion']);
-    },
-    'foundHandler' => create(ControllerInvoker::class)
-        ->constructor(get('foundHandler.invoker')),
-    'foundHandler.invoker' => function (ContainerInterface $c) {
-        $resolvers = [
-            // Inject parameters by name first
-            new AssociativeArrayResolver,
-            // Then inject services by type-hints for those that weren't resolved
-            new TypeHintContainerResolver($c),
-            // Then fall back on parameters default values for optional route parameters
-            new DefaultValueResolver(),
-        ];
-        return new Invoker(new ResolverChain($resolvers), $c);
-    },
-
-    'callableResolver' => autowire(CallableResolver::class),
-
-];
diff --git a/tests/ApplicationTest.php b/tests/ApplicationTest.php
index 7b228d2..697f8b6 100644
--- a/tests/ApplicationTest.php
+++ b/tests/ApplicationTest.php
@@ -2,10 +2,9 @@
 
 namespace DI\Bridge\Slim\Test;
 
-use DI\Bridge\Slim\App;
+use DI\Bridge\Slim\Bridge;
 use DI\Bridge\Slim\Test\Mock\RequestFactory;
 use PHPUnit\Framework\TestCase;
-use Slim\Http\Response;
 
 class ApplicationTest extends TestCase
 {
@@ -14,14 +13,15 @@ class ApplicationTest extends TestCase
      */
     public function runs()
     {
-        $app = new App;
+        $app = Bridge::create();
 
         $called = false;
-        $app->get('/', function () use (&$called) {
+        $app->get('/', function ($request, $response) use (&$called) {
             $called = true;
+            return $response;
         });
+        $app->handle(RequestFactory::create());
 
-        $app->callMiddlewareStack(RequestFactory::create(), new Response);
         $this->assertTrue($called);
     }
 }
diff --git a/tests/ContainerTest.php b/tests/ContainerTest.php
deleted file mode 100644
index 2b8ea72..0000000
--- a/tests/ContainerTest.php
+++ /dev/null
@@ -1,59 +0,0 @@
-<?php
-
-namespace DI\Bridge\Slim\Test;
-
-use DI\Bridge\Slim\App;
-use PHPUnit\Framework\TestCase;
-
-class ContainerTest extends TestCase
-{
-    /**
-     * Slim expects some container entries to exist. To check that, we get all entries from the
-     * default Slim container and check that they exist in PHP-DI.
-     *
-     * @test
-     */
-    public function provides_mandatory_container_entries()
-    {
-        $slimDefault = new \Slim\App;
-        $slimPhpDi = new App;
-
-        /** @var \Slim\Container $defaultContainer */
-        $defaultContainer = $slimDefault->getContainer();
-        /** @var \DI\Container $phpdiContainer */
-        $phpdiContainer = $slimPhpDi->getContainer();
-
-        $expectedEntries = $defaultContainer->keys();
-
-        foreach ($expectedEntries as $expectedEntry) {
-            $this->assertTrue($phpdiContainer->has($expectedEntry), "Container entry $expectedEntry is missing");
-            // Check that the service is created without exception
-            $phpdiContainer->get($expectedEntry);
-        }
-    }
-
-    /**
-     * Slim expects some config options to exist.
-     *
-     * @test
-     */
-    public function provides_default_config_options()
-    {
-        $slimDefault = new \Slim\App;
-        $slimPhpDi = new App;
-
-        /** @var \Slim\Container $defaultContainer */
-        $defaultContainer = $slimDefault->getContainer();
-        /** @var \DI\Container $phpdiContainer */
-        $phpdiContainer = $slimPhpDi->getContainer();
-
-        $expectedOptions = $defaultContainer->get('settings');
-        $actualOptions = $phpdiContainer->get('settings');
-
-        foreach ($expectedOptions as $name => $value) {
-            $this->assertArrayHasKey($name, $actualOptions);
-            // Has the same default value
-            $this->assertEquals($value, $actualOptions[$name]);
-        }
-    }
-}
diff --git a/tests/ErrorTest.php b/tests/ErrorTest.php
deleted file mode 100644
index d008157..0000000
--- a/tests/ErrorTest.php
+++ /dev/null
@@ -1,98 +0,0 @@
-<?php
-
-namespace DI\Bridge\Slim\Test;
-
-use DI\Bridge\Slim\App;
-use DI\ContainerBuilder;
-use Slim\Handlers\Error;
-use PHPUnit\Framework\TestCase;
-use DI\Bridge\Slim\Test\Mock\RequestFactory;
-use Slim\Http\Response;
-
-class ErrorTest extends TestCase
-{
-    /**
-     * Test default errorHandler
-     *
-     * @test
-     */
-    public function default_exception_handling()
-    {
-        // Send error_log output to a temp file.
-        $logFile = tempnam(sys_get_temp_dir(), 'slim-bridge');
-        ini_set('error_log', $logFile);
-
-        $app = new App;
-        $c = $app->getContainer();
-
-        // Sanity check - default for displayErrorDetails should be false
-        $displayErrorDetails = $c->get('settings.displayErrorDetails');
-        $this->assertFalse($displayErrorDetails);
-
-        /** @var Error $error */
-        $error = $c->get('errorHandler');
-        $response = $error(RequestFactory::create('/'), new Response(), new \Exception());
-        $reasonPhrase = $response->getReasonPhrase();
-        $this->assertEquals('Internal Server Error', $reasonPhrase);
-
-        $log = file_get_contents($logFile);
-        $this->assertNotEmpty($log);
-    }
-
-    /**
-     * Test custom errorHandler
-     *
-     * @test
-     */
-    public function custom_exception_handling()
-    {
-        // Send error_log output to a temp file.
-        $logFile = tempnam(sys_get_temp_dir(), 'slim-bridge');
-        ini_set('error_log', $logFile);
-
-        $app = new BridgeApp(
-            [
-                'settings.displayErrorDetails' => true,
-                'settings.outputBuffering' => 'append'
-            ]);
-        $c = $app->getContainer();
-
-        // Sanity checks
-        $displayErrorDetails = $c->get('settings.displayErrorDetails');
-        $this->assertTrue($displayErrorDetails);
-        $outputBuffering = $c->get('settings.outputBuffering');
-        $this->assertEquals('append', $outputBuffering);
-
-        /** @var Error $error */
-        $error = $c->get('errorHandler');
-
-        $response = $error(RequestFactory::create('/'), new Response(), new \Exception());
-        $reasonPhrase = $response->getReasonPhrase();
-        $this->assertEquals('Internal Server Error', $reasonPhrase);
-
-        $log = file_get_contents($logFile);
-        $this->assertEmpty($log);
-    }
-}
-
-/**
- * Class BridgeApp
- *
- * Override the configuration via the configureContainer() hook.
- */
-class BridgeApp extends App
-{
-    protected $config = [];
-
-    public function __construct(array $config)
-    {
-        $this->config = $config;
-
-        parent::__construct();
-    }
-
-    public function configureContainer(ContainerBuilder $builder)
-    {
-        $builder->addDefinitions($this->config);
-    }
-}
diff --git a/tests/Fixture/Middleware.php b/tests/Fixture/Middleware.php
deleted file mode 100644
index 132fa84..0000000
--- a/tests/Fixture/Middleware.php
+++ /dev/null
@@ -1,15 +0,0 @@
-<?php
-
-namespace DI\Bridge\Slim\Test\Fixture;
-
-use Psr\Http\Message\ResponseInterface;
-use Psr\Http\Message\ServerRequestInterface;
-
-class Middleware
-{
-    public function __invoke(ServerRequestInterface $request, ResponseInterface $response, callable $next)
-    {
-        $response->getBody()->write('Hello world!');
-        return $response;
-    }
-}
diff --git a/tests/Fixture/UserController.php b/tests/Fixture/UserController.php
index b0e85d3..85f8322 100644
--- a/tests/Fixture/UserController.php
+++ b/tests/Fixture/UserController.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 namespace DI\Bridge\Slim\Test\Fixture;
 
diff --git a/tests/MiddlewareTest.php b/tests/MiddlewareTest.php
index 239f56e..8349647 100644
--- a/tests/MiddlewareTest.php
+++ b/tests/MiddlewareTest.php
@@ -1,13 +1,13 @@
-<?php
+<?php declare(strict_types=1);
 
 namespace DI\Bridge\Slim\Test;
 
-use DI\Bridge\Slim\App;
+use DI\Bridge\Slim\Bridge;
 use DI\Bridge\Slim\Test\Mock\RequestFactory;
 use PHPUnit\Framework\TestCase;
-use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
-use Slim\Http\Response;
+use Psr\Http\Server\RequestHandlerInterface;
+use Zend\Diactoros\Response\TextResponse;
 
 class MiddlewareTest extends TestCase
 {
@@ -16,14 +16,13 @@ class MiddlewareTest extends TestCase
      */
     public function invokes_closure_middleware()
     {
-        $app = new App;
-        $app->add(function (ServerRequestInterface $request, ResponseInterface $response, callable $next) {
-            $response->getBody()->write('Hello ' . $request->getQueryParams()['foo']);
-            return $response;
+        $app = Bridge::create();
+        $app->add(function (ServerRequestInterface $request, RequestHandlerInterface $next) {
+            return new TextResponse('Hello ' . $request->getQueryParams()['foo']);
         });
         $app->get('/', function () {});
 
-        $response = $app->callMiddlewareStack(RequestFactory::create('/', 'foo=matt'), new Response);
+        $response = $app->handle(RequestFactory::create('/', 'foo=matt'));
 
         $this->assertEquals('Hello matt', $response->getBody()->__toString());
     }
diff --git a/tests/Mock/RequestFactory.php b/tests/Mock/RequestFactory.php
index ccacb93..5b13ab8 100644
--- a/tests/Mock/RequestFactory.php
+++ b/tests/Mock/RequestFactory.php
@@ -1,18 +1,24 @@
-<?php
+<?php declare(strict_types=1);
 
 namespace DI\Bridge\Slim\Test\Mock;
 
-use Slim\Http\Environment;
-use Slim\Http\Request;
+use Psr\Http\Message\ServerRequestInterface;
+use Zend\Diactoros\ServerRequest;
 
 class RequestFactory
 {
-    public static function create($uri = '/', $queryString = '')
+    public static function create($uri = '/', $queryString = ''): ServerRequestInterface
     {
-        return Request::createFromEnvironment(Environment::mock([
-            'SCRIPT_NAME'  => 'index.php',
-            'REQUEST_URI'  => $uri,
-            'QUERY_STRING' => $queryString,
-        ]));
+        parse_str($queryString, $queryParams);
+        return new ServerRequest(
+            [],
+            [],
+            $uri,
+            'GET',
+            'php://temp',
+            [],
+            [],
+            $queryParams
+        );
     }
 }
diff --git a/tests/RoutingTest.php b/tests/RoutingTest.php
index 94bc656..dc55454 100644
--- a/tests/RoutingTest.php
+++ b/tests/RoutingTest.php
@@ -1,14 +1,14 @@
-<?php
+<?php declare(strict_types=1);
 
 namespace DI\Bridge\Slim\Test;
 
-use DI\Bridge\Slim\App;
+use DI\Bridge\Slim\Bridge;
 use DI\Bridge\Slim\Test\Fixture\UserController;
 use DI\Bridge\Slim\Test\Mock\RequestFactory;
 use PHPUnit\Framework\TestCase;
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
-use Slim\Http\Response;
+use Psr\Http\Server\RequestHandlerInterface;
 
 class RoutingTest extends TestCase
 {
@@ -17,15 +17,16 @@ class RoutingTest extends TestCase
      */
     public function injects_request_and_response()
     {
-        $app = new App;
+        $app = Bridge::create();
+
         // Response and request and inversed to check that they are correctly injected by name
         $app->get('/', function (ResponseInterface $response, ServerRequestInterface $request) {
             $response->getBody()->write('Hello ' . $request->getQueryParams()['foo']);
             return $response;
         });
 
-        $response = $app->callMiddlewareStack(RequestFactory::create('/', 'foo=matt'), new Response);
-        $this->assertEquals('Hello matt', $response->getBody()->__toString());
+        $response = $app->handle(RequestFactory::create('/', 'foo=matt'));
+        $this->assertEquals('Hello matt', (string) $response->getBody());
     }
 
     /**
@@ -33,14 +34,14 @@ public function injects_request_and_response()
      */
     public function injects_route_placeholder()
     {
-        $app = new App;
+        $app = Bridge::create();
         $app->get('/{name}', function ($name, $response) {
             $response->getBody()->write('Hello ' . $name);
             return $response;
         });
 
-        $response = $app->callMiddlewareStack(RequestFactory::create('/matt'), new Response);
-        $this->assertEquals('Hello matt', $response->getBody()->__toString());
+        $response = $app->handle(RequestFactory::create('/matt'));
+        $this->assertEquals('Hello matt', (string) $response->getBody());
     }
 
     /**
@@ -48,13 +49,13 @@ public function injects_route_placeholder()
      */
     public function injects_optional_route_placeholder()
     {
-        $app = new App;
+        $app = Bridge::create();
         $app->get('/[{name}]', function ($response, $name = null) {
             $response->getBody()->write('Hello ' . $name);
             return $response;
         });
 
-        $response = $app->callMiddlewareStack(RequestFactory::create('/matt'), new Response);
+        $response = $app->handle(RequestFactory::create('/matt'));
         $this->assertEquals('Hello matt', (string) $response->getBody());
     }
 
@@ -63,13 +64,13 @@ public function injects_optional_route_placeholder()
      */
     public function injects_default_value_in_optional_route_placeholder()
     {
-        $app = new App;
+        $app = Bridge::create();
         $app->get('/[{name}]', function ($response, $name = 'john doe') {
             $response->getBody()->write('Hello ' . $name);
             return $response;
         });
 
-        $response = $app->callMiddlewareStack(RequestFactory::create('/'), new Response);
+        $response = $app->handle(RequestFactory::create());
         $this->assertEquals('Hello john doe', (string) $response->getBody());
     }
 
@@ -78,18 +79,18 @@ public function injects_default_value_in_optional_route_placeholder()
      */
     public function injects_request_attribute()
     {
-        $app = new App;
+        $app = Bridge::create();
         // Let's add a middleware that adds a request attribute
-        $app->add(function (ServerRequestInterface $request, $response, $next) {
-            return $next($request->withAttribute('name', 'Bob'), $response);
+        $app->add(function (ServerRequestInterface $request, RequestHandlerInterface $next) {
+            return $next->handle($request->withAttribute('name', 'Bob'));
         });
         $app->get('/', function ($name, $response) {
             $response->getBody()->write('Hello ' . $name);
             return $response;
         });
 
-        $response = $app->callMiddlewareStack(RequestFactory::create('/'), new Response);
-        $this->assertEquals('Hello Bob', $response->getBody()->__toString());
+        $response = $app->handle(RequestFactory::create());
+        $this->assertEquals('Hello Bob', (string) $response->getBody());
     }
 
     /**
@@ -97,16 +98,16 @@ public function injects_request_attribute()
      */
     public function injects_route_placeholder_over_request_attribute()
     {
-        $app = new App;
-        $app->add(function (ServerRequestInterface $request, $response, $next) {
-            return $next($request->withAttribute('name', 'Bob'), $response);
+        $app = Bridge::create();
+        $app->add(function (ServerRequestInterface $request, RequestHandlerInterface $next) {
+            return $next->handle($request->withAttribute('name', 'Bob'));
         });
         $app->get('/{name}', function ($name, $response) {
             $response->getBody()->write('Hello ' . $name);
             return $response;
         });
 
-        $response = $app->callMiddlewareStack(RequestFactory::create('/matt'), new Response);
+        $response = $app->handle(RequestFactory::create('/matt'));
         // The route placeholder has priority over the request attribute
         $this->assertEquals('Hello matt', (string) $response->getBody());
     }
@@ -116,10 +117,10 @@ public function injects_route_placeholder_over_request_attribute()
      */
     public function resolve_controller_from_container()
     {
-        $app = new App;
+        $app = Bridge::create();
         $app->get('/', [UserController::class, 'dashboard']);
 
-        $response = $app->callMiddlewareStack(RequestFactory::create(), new Response);
-        $this->assertEquals('Hello world!', $response->getBody()->__toString());
+        $response = $app->handle(RequestFactory::create());
+        $this->assertEquals('Hello world!', (string) $response->getBody());
     }
 }