diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..73b98b0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,5 @@
+/composer.lock
+/vendor/
+
+phpunit.xml
+.phpunit.result.cache
diff --git a/composer.json b/composer.json
index edb1fc3..521233f 100644
--- a/composer.json
+++ b/composer.json
@@ -16,5 +16,10 @@
     },
     "extra": {
         "contao-manager-plugin": "Ameotoko\\BackendRedirect\\ContaoManager\\Plugin"
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "Ameotoko\\BackendRedirect\\Test\\": "tests/"
+        }
     }
 }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
new file mode 100644
index 0000000..bce355f
--- /dev/null
+++ b/phpunit.xml.dist
@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/8.5/phpunit.xsd"
+         bootstrap="vendor/autoload.php"
+         executionOrder="depends,defects"
+         forceCoversAnnotation="true"
+         beStrictAboutCoversAnnotation="true"
+         beStrictAboutOutputDuringTests="true"
+         beStrictAboutTodoAnnotatedTests="true"
+         convertDeprecationsToExceptions="true"
+         verbose="true">
+    <php>
+        <const name="REQUEST_TOKEN" value="3745f4756fg" />
+    </php>
+    <testsuites>
+        <testsuite name="default">
+            <directory>tests</directory>
+        </testsuite>
+    </testsuites>
+
+    <filter>
+        <whitelist processUncoveredFilesFromWhitelist="true">
+            <directory suffix=".php">src</directory>
+        </whitelist>
+    </filter>
+</phpunit>
diff --git a/tests/Controller/RedirectControllerTest.php b/tests/Controller/RedirectControllerTest.php
new file mode 100644
index 0000000..492d489
--- /dev/null
+++ b/tests/Controller/RedirectControllerTest.php
@@ -0,0 +1,62 @@
+<?php
+/**
+ * @author Andrey Vinichenko <andrey.vinichenko@gmail.com>
+ */
+
+namespace Ameotoko\BackendRedirect\Test\Controller;
+
+use Ameotoko\BackendRedirect\Controller\RedirectController;
+use Contao\System;
+use Contao\TestCase\ContaoTestCase;
+use Symfony\Component\HttpFoundation\RedirectResponse;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\RequestStack;
+use Symfony\Component\Routing\Router;
+
+class RedirectControllerTest extends ContaoTestCase
+{
+    public function testBackendRedirectResponse(): void
+    {
+        $request = Request::create('https://localhost/contao/redirect?do=members&act=edit&id=42');
+        $request->attributes->set('_contao_referer_id', '_OY4TOxP');
+
+        \define('TL_SCRIPT', substr($request->getBaseUrl().$request->getPathInfo(), \strlen($request->getBasePath().'/')));
+
+        $requestStack = $this->createMock(RequestStack::class);
+        $requestStack->method('getCurrentRequest')->willReturn($request);
+
+        $container = $this->getContainerWithContaoConfiguration();
+        $container->set('request_stack', $requestStack);
+
+        $framework = $this->mockContaoFramework();
+        $framework->expects($this->atLeastOnce())->method('initialize');
+
+        System::setContainer($container);
+
+        $router = $this->createMock(Router::class);
+        $router->method('generate')->with('contao_backend')->willReturn('/contao');
+
+        $controller = new RedirectController();
+
+        /** @var RedirectResponse $response */
+        $response = $controller($request, $framework, $router);
+
+        $this->assertInstanceOf(RedirectResponse::class, $response);
+
+        $parsedUrl = parse_url($response->getTargetUrl());
+
+        // Path must become /contao instead of /contao/redirect
+        $this->assertSame('/contao', $parsedUrl['path']);
+
+        parse_str($parsedUrl['query'], $query);
+
+        // Original query params must be preserved
+        $this->assertSame('members', $query['do']);
+        $this->assertSame('edit', $query['act']);
+        $this->assertSame('42', $query['id']);
+
+        // ref and request token must be added to the response url
+        $this->assertSame('_OY4TOxP', $query['ref']);
+        $this->assertArrayHasKey('rt', $query);
+    }
+}