diff --git a/src/Symfony/Bundle/WebProfilerBundle/CHANGELOG.md b/src/Symfony/Bundle/WebProfilerBundle/CHANGELOG.md
index 539d814d2a438..50787452ea277 100644
--- a/src/Symfony/Bundle/WebProfilerBundle/CHANGELOG.md
+++ b/src/Symfony/Bundle/WebProfilerBundle/CHANGELOG.md
@@ -5,6 +5,7 @@ CHANGELOG
 ---
 
  * Add `ajax_replace` option for replacing toolbar on AJAX requests
+ * Show debug bar when using a streamed response
 
 7.2
 ---
diff --git a/src/Symfony/Bundle/WebProfilerBundle/EventListener/WebDebugToolbarListener.php b/src/Symfony/Bundle/WebProfilerBundle/EventListener/WebDebugToolbarListener.php
index de7bb7b001ca0..d1eeeee1aa616 100644
--- a/src/Symfony/Bundle/WebProfilerBundle/EventListener/WebDebugToolbarListener.php
+++ b/src/Symfony/Bundle/WebProfilerBundle/EventListener/WebDebugToolbarListener.php
@@ -17,6 +17,7 @@
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpFoundation\Session\Flash\AutoExpireFlashBag;
+use Symfony\Component\HttpFoundation\StreamedResponse;
 use Symfony\Component\HttpKernel\DataCollector\DumpDataCollector;
 use Symfony\Component\HttpKernel\Event\ResponseEvent;
 use Symfony\Component\HttpKernel\KernelEvents;
@@ -110,7 +111,14 @@ public function onKernelResponse(ResponseEvent $event): void
                 $session->getFlashBag()->setAll($session->getFlashBag()->peekAll());
             }
 
-            $response->setContent($this->twig->render('@WebProfiler/Profiler/toolbar_redirect.html.twig', ['location' => $response->headers->get('Location'), 'host' => $request->getSchemeAndHttpHost()]));
+            if ($response instanceof StreamedResponse) {
+                $twig = $this->twig;
+                $response->setCallback(function () use ($twig, $request, $response): void {
+                    echo $twig->render('@WebProfiler/Profiler/toolbar_redirect.html.twig', ['location' => $response->headers->get('Location'), 'host' => $request->getSchemeAndHttpHost()]);
+                });
+            } else {
+                $response->setContent($this->twig->render('@WebProfiler/Profiler/toolbar_redirect.html.twig', ['location' => $response->headers->get('Location'), 'host' => $request->getSchemeAndHttpHost()]));
+            }
             $response->setStatusCode(200);
             $response->headers->remove('Location');
         }
@@ -133,26 +141,51 @@ public function onKernelResponse(ResponseEvent $event): void
      */
     protected function injectToolbar(Response $response, Request $request, array $nonces): void
     {
-        $content = $response->getContent();
-        $pos = strripos($content, '</body>');
-
-        if (false !== $pos) {
-            $toolbar = "\n".str_replace("\n", '', $this->twig->render(
-                '@WebProfiler/Profiler/toolbar_js.html.twig',
-                [
-                    'full_stack' => class_exists(FullStack::class),
-                    'excluded_ajax_paths' => $this->excludedAjaxPaths,
-                    'token' => $response->headers->get('X-Debug-Token'),
-                    'request' => $request,
-                    'csp_script_nonce' => $nonces['csp_script_nonce'] ?? null,
-                    'csp_style_nonce' => $nonces['csp_style_nonce'] ?? null,
-                ]
-            ))."\n";
-            $content = substr($content, 0, $pos).$toolbar.substr($content, $pos);
-            $response->setContent($content);
+        if ($response instanceof StreamedResponse) {
+            $callback = $response->getCallback();
+            $toolbarHTMLContent = "\n".str_replace("\n", '', $this->getToolbarHTML($request, $response->headers->get('X-Debug-Token'), $nonces))."\n";
+            $injectedCallback = static function () use ($toolbarHTMLContent, $callback): void {
+                ob_start(function (string $buffer, int $phase) use ($toolbarHTMLContent): string {
+                    $pos = strripos($buffer, '</body>');
+                    if (false !== $pos) {
+                        $buffer = substr($buffer, 0, $pos).$toolbarHTMLContent.substr($buffer, $pos);
+                    }
+
+                    return $buffer;
+                }, 8); // length of '</body>'
+
+                ($callback)();
+                ob_end_flush();
+            };
+            $response->setCallback($injectedCallback);
+        } else {
+            $content = $response->getContent();
+            $pos = strripos($content, '</body>');
+
+            if (false !== $pos) {
+                $toolbar = "\n".str_replace("\n", '', $this->getToolbarHTML($request, $response->headers->get('X-Debug-Token'), $nonces))."\n";
+
+                $content = substr($content, 0, $pos).$toolbar.substr($content, $pos);
+                $response->setContent($content);
+            }
         }
     }
 
+    private function getToolbarHTML(Request $request, ?string $debugToken, array $nonces): string
+    {
+        return $this->twig->render(
+            '@WebProfiler/Profiler/toolbar_js.html.twig',
+            [
+                'full_stack' => class_exists(FullStack::class),
+                'excluded_ajax_paths' => $this->excludedAjaxPaths,
+                'token' => $debugToken,
+                'request' => $request,
+                'csp_script_nonce' => $nonces['csp_script_nonce'] ?? null,
+                'csp_style_nonce' => $nonces['csp_style_nonce'] ?? null,
+            ]
+        );
+    }
+
     public static function getSubscribedEvents(): array
     {
         return [
diff --git a/src/Symfony/Bundle/WebProfilerBundle/Tests/EventListener/WebDebugToolbarListenerTest.php b/src/Symfony/Bundle/WebProfilerBundle/Tests/EventListener/WebDebugToolbarListenerTest.php
index ff9bd096fb13f..bd4ca434596fd 100644
--- a/src/Symfony/Bundle/WebProfilerBundle/Tests/EventListener/WebDebugToolbarListenerTest.php
+++ b/src/Symfony/Bundle/WebProfilerBundle/Tests/EventListener/WebDebugToolbarListenerTest.php
@@ -28,7 +28,7 @@ class WebDebugToolbarListenerTest extends TestCase
     /**
      * @dataProvider getInjectToolbarTests
      */
-    public function testInjectToolbar($content, $expected)
+    public function testInjectToolbar(string $content, string $expected)
     {
         $listener = new WebDebugToolbarListener($this->getTwigMock());
         $m = new \ReflectionMethod($listener, 'injectToolbar');
@@ -60,7 +60,7 @@ public static function getInjectToolbarTests()
     /**
      * @dataProvider provideRedirects
      */
-    public function testHtmlRedirectionIsIntercepted($statusCode)
+    public function testHtmlRedirectionIsIntercepted(int $statusCode)
     {
         $response = new Response('Some content', $statusCode);
         $response->headers->set('X-Debug-Token', 'xxxxxxxx');
@@ -75,7 +75,7 @@ public function testHtmlRedirectionIsIntercepted($statusCode)
 
     public function testNonHtmlRedirectionIsNotIntercepted()
     {
-        $response = new Response('Some content', '301');
+        $response = new Response('Some content', 301);
         $response->headers->set('X-Debug-Token', 'xxxxxxxx');
         $event = new ResponseEvent($this->createMock(Kernel::class), new Request([], [], ['_format' => 'json']), HttpKernelInterface::MAIN_REQUEST, $response);
 
@@ -136,7 +136,7 @@ public function testToolbarIsNotInjectedOnContentDispositionAttachment()
      *
      * @dataProvider provideRedirects
      */
-    public function testToolbarIsNotInjectedOnRedirection($statusCode)
+    public function testToolbarIsNotInjectedOnRedirection(int $statusCode)
     {
         $response = new Response('<html><head></head><body></body></html>', $statusCode);
         $response->headers->set('X-Debug-Token', 'xxxxxxxx');
@@ -417,7 +417,7 @@ public function testAjaxReplaceHeaderOnEnabledAndXHRButPreviouslySet()
         $this->assertSame('0', $response->headers->get('Symfony-Debug-Toolbar-Replace'));
     }
 
-    protected function getTwigMock($render = 'WDT')
+    protected function getTwigMock(string $render = 'WDT')
     {
         $templating = $this->createMock(Environment::class);
         $templating->expects($this->any())
diff --git a/src/Symfony/Bundle/WebProfilerBundle/Tests/EventListener/WebDebugToolbarStreamedResponseListenerTest.php b/src/Symfony/Bundle/WebProfilerBundle/Tests/EventListener/WebDebugToolbarStreamedResponseListenerTest.php
new file mode 100644
index 0000000000000..86f15c52d99ad
--- /dev/null
+++ b/src/Symfony/Bundle/WebProfilerBundle/Tests/EventListener/WebDebugToolbarStreamedResponseListenerTest.php
@@ -0,0 +1,386 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bundle\WebProfilerBundle\Tests\EventListener;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Bundle\WebProfilerBundle\Csp\ContentSecurityPolicyHandler;
+use Symfony\Bundle\WebProfilerBundle\EventListener\WebDebugToolbarListener;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\StreamedResponse;
+use Symfony\Component\HttpKernel\DataCollector\DumpDataCollector;
+use Symfony\Component\HttpKernel\Event\ResponseEvent;
+use Symfony\Component\HttpKernel\HttpKernelInterface;
+use Symfony\Component\HttpKernel\Kernel;
+use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
+use Twig\Environment;
+
+class WebDebugToolbarStreamedResponseListenerTest extends TestCase
+{
+    /**
+     * @dataProvider getInjectToolbarTests
+     */
+    public function testInjectToolbar(string $content, string $expected)
+    {
+        $listener = new WebDebugToolbarListener($this->getTwigMock());
+        $m = new \ReflectionMethod($listener, 'injectToolbar');
+
+        $response = new StreamedResponse($this->createCallbackFromContent($content));
+
+        $m->invoke($listener, $response, Request::create('/'), ['csp_script_nonce' => 'scripto', 'csp_style_nonce' => 'stylo']);
+        $this->assertEquals($expected, $this->getContentFromStreamedResponse($response));
+    }
+
+    public static function getInjectToolbarTests()
+    {
+        return [
+            ['<html><head></head><body></body></html>', "<html><head></head><body>\nWDT\n</body></html>"],
+            ['<html>
+            <head></head>
+            <body>
+            <textarea><html><head></head><body></body></html></textarea>
+            </body>
+            </html>', "<html>
+            <head></head>
+            <body>
+            <textarea><html><head></head><body></body></html></textarea>
+            \nWDT\n</body>
+            </html>"],
+        ];
+    }
+
+    /**
+     * @dataProvider provideRedirects
+     */
+    public function testHtmlRedirectionIsIntercepted(int $statusCode)
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('Some content'), $statusCode);
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock('Redirection'), true);
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals(200, $response->getStatusCode());
+        $this->assertEquals('Redirection', $this->getContentFromStreamedResponse($response));
+    }
+
+    public function testNonHtmlRedirectionIsNotIntercepted()
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('Some content'), 301);
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request([], [], ['_format' => 'json']), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock('Redirection'), true);
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals(301, $response->getStatusCode());
+        $this->assertEquals('Some content', $this->getContentFromStreamedResponse($response));
+    }
+
+    public function testToolbarIsInjected()
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('<html><head></head><body></body></html>'));
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock());
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals("<html><head></head><body>\nWDT\n</body></html>", $this->getContentFromStreamedResponse($response));
+    }
+
+    /**
+     * @depends testToolbarIsInjected
+     */
+    public function testToolbarIsNotInjectedOnNonHtmlContentType()
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('<html><head></head><body></body></html>'));
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+        $response->headers->set('Content-Type', 'text/xml');
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock());
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals('<html><head></head><body></body></html>', $this->getContentFromStreamedResponse($response));
+    }
+
+    /**
+     * @depends testToolbarIsInjected
+     */
+    public function testToolbarIsNotInjectedOnContentDispositionAttachment()
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('<html><head></head><body></body></html>'));
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+        $response->headers->set('Content-Disposition', 'attachment; filename=test.html');
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock());
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals('<html><head></head><body></body></html>', $this->getContentFromStreamedResponse($response));
+    }
+
+    /**
+     * @depends testToolbarIsInjected
+     *
+     * @dataProvider provideRedirects
+     */
+    public function testToolbarIsNotInjectedOnRedirection(int $statusCode)
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('<html><head></head><body></body></html>'), $statusCode);
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock());
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals('<html><head></head><body></body></html>', $this->getContentFromStreamedResponse($response));
+    }
+
+    public static function provideRedirects(): array
+    {
+        return [
+            [301],
+            [302],
+        ];
+    }
+
+    /**
+     * @depends testToolbarIsInjected
+     */
+    public function testToolbarIsNotInjectedWhenThereIsNoNoXDebugTokenResponseHeader()
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('<html><head></head><body></body></html>'));
+
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock());
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals('<html><head></head><body></body></html>', $this->getContentFromStreamedResponse($response));
+    }
+
+    /**
+     * @depends testToolbarIsInjected
+     */
+    public function testToolbarIsNotInjectedWhenOnSubRequest()
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('<html><head></head><body></body></html>'));
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::SUB_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock());
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals('<html><head></head><body></body></html>', $this->getContentFromStreamedResponse($response));
+    }
+
+    /**
+     * @depends testToolbarIsInjected
+     */
+    public function testToolbarIsNotInjectedOnIncompleteHtmlResponses()
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('<div>Some content</div>'));
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock());
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals('<div>Some content</div>', $this->getContentFromStreamedResponse($response));
+    }
+
+    /**
+     * @depends testToolbarIsInjected
+     */
+    public function testToolbarIsNotInjectedOnXmlHttpRequests()
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('<html><head></head><body></body></html>'));
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+
+        $request = new Request();
+        $request->headers->set('X-Requested-With', 'XMLHttpRequest');
+
+        $event = new ResponseEvent($this->createMock(Kernel::class), $request, HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock());
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals('<html><head></head><body></body></html>', $this->getContentFromStreamedResponse($response));
+    }
+
+    /**
+     * @depends testToolbarIsInjected
+     */
+    public function testToolbarIsNotInjectedOnNonHtmlRequests()
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('<html><head></head><body></body></html>'));
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request([], [], ['_format' => 'json']), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock());
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals('<html><head></head><body></body></html>', $this->getContentFromStreamedResponse($response));
+    }
+
+    public function testXDebugUrlHeader()
+    {
+        $response = new StreamedResponse();
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+
+        $urlGenerator = $this->createMock(UrlGeneratorInterface::class);
+        $urlGenerator
+            ->expects($this->once())
+            ->method('generate')
+            ->with('_profiler', ['token' => 'xxxxxxxx'], UrlGeneratorInterface::ABSOLUTE_URL)
+            ->willReturn('http://mydomain.com/_profiler/xxxxxxxx')
+        ;
+
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock(), false, WebDebugToolbarListener::ENABLED, $urlGenerator);
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals('http://mydomain.com/_profiler/xxxxxxxx', $response->headers->get('X-Debug-Token-Link'));
+    }
+
+    public function testThrowingUrlGenerator()
+    {
+        $response = new StreamedResponse();
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+
+        $urlGenerator = $this->createMock(UrlGeneratorInterface::class);
+        $urlGenerator
+            ->expects($this->once())
+            ->method('generate')
+            ->with('_profiler', ['token' => 'xxxxxxxx'])
+            ->willThrowException(new \Exception('foo'))
+        ;
+
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock(), false, WebDebugToolbarListener::ENABLED, $urlGenerator);
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals('Exception: foo', $response->headers->get('X-Debug-Error'));
+    }
+
+    public function testThrowingErrorCleanup()
+    {
+        $response = new StreamedResponse();
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+
+        $urlGenerator = $this->createMock(UrlGeneratorInterface::class);
+        $urlGenerator
+            ->expects($this->once())
+            ->method('generate')
+            ->with('_profiler', ['token' => 'xxxxxxxx'])
+            ->willThrowException(new \Exception("This\nmultiline\r\ntabbed text should\tcome out\r on\n \ta single plain\r\nline"))
+        ;
+
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock(), false, WebDebugToolbarListener::ENABLED, $urlGenerator);
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals('Exception: This multiline tabbed text should come out on a single plain line', $response->headers->get('X-Debug-Error'));
+    }
+
+    public function testCspIsDisabledIfDumperWasUsed()
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('<html><head></head><body></body></html>'));
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $cspHandler = $this->createMock(ContentSecurityPolicyHandler::class);
+        $cspHandler->expects($this->once())
+            ->method('disableCsp');
+        $dumpDataCollector = $this->createMock(DumpDataCollector::class);
+        $dumpDataCollector->expects($this->once())
+            ->method('getDumpsCount')
+            ->willReturn(1);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock(), false, WebDebugToolbarListener::ENABLED, null, '', $cspHandler, $dumpDataCollector);
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals("<html><head></head><body>\nWDT\n</body></html>", $this->getContentFromStreamedResponse($response));
+    }
+
+    public function testCspIsKeptEnabledIfDumperWasNotUsed()
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('<html><head></head><body></body></html>'));
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $cspHandler = $this->createMock(ContentSecurityPolicyHandler::class);
+        $cspHandler->expects($this->never())
+            ->method('disableCsp');
+        $dumpDataCollector = $this->createMock(DumpDataCollector::class);
+        $dumpDataCollector->expects($this->once())
+            ->method('getDumpsCount')
+            ->willReturn(0);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock(), false, WebDebugToolbarListener::ENABLED, null, '', $cspHandler, $dumpDataCollector);
+        $listener->onKernelResponse($event);
+
+        $this->assertEquals("<html><head></head><body>\nWDT\n</body></html>", $this->getContentFromStreamedResponse($response));
+    }
+
+    public function testNullContentTypeWithNoDebugEnv()
+    {
+        $response = new StreamedResponse($this->createCallbackFromContent('<html><head></head><body></body></html>'));
+        $response->headers->set('Content-Type', null);
+        $response->headers->set('X-Debug-Token', 'xxxxxxxx');
+
+        $event = new ResponseEvent($this->createMock(Kernel::class), new Request(), HttpKernelInterface::MAIN_REQUEST, $response);
+
+        $listener = new WebDebugToolbarListener($this->getTwigMock(), false, WebDebugToolbarListener::ENABLED, null);
+        $listener->onKernelResponse($event);
+
+        $this->expectNotToPerformAssertions();
+    }
+
+    protected function getTwigMock(string $render = 'WDT')
+    {
+        $templating = $this->createMock(Environment::class);
+        $templating->expects($this->any())
+            ->method('render')
+            ->willReturn($render);
+
+        return $templating;
+    }
+
+    private function createCallbackFromContent(string $content): callable
+    {
+        return function () use ($content) {
+            echo $content;
+        };
+    }
+
+    private function getContentFromStreamedResponse(StreamedResponse $response): string
+    {
+        ob_start();
+        $response->sendContent();
+        $content = ob_get_contents();
+        ob_end_clean();
+
+        return $content;
+    }
+}