fix: properly forward return urls where missing

tests/Twig/ForwardedReturnUrlTest.php

@@ -0,0 +1,52 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Twig;
+
+use App\Twig\AppRuntime;
+use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\RequestStack;
+
+class ForwardedReturnUrlTest extends KernelTestCase
+{
+    private RequestStack $requestStack;
+    private AppRuntime $appRuntime;
+
+    protected function setUp(): void
+    {
+        self::bootKernel();
+
+        $this->requestStack = self::getContainer()->get(RequestStack::class);
+        $this->appRuntime = self::getContainer()->get(AppRuntime::class);
+    }
+
+    public function testTheReturnUrlIsPassedOnUntouched(): void
+    {
+        $encoded = rawurlencode('/administrative/assignment?page=3');
+        $this->requestStack->push(Request::create('/administrative/assignment/detail/abc?r='.$encoded));
+
+        // The raw query value, handed straight back to the url generator, which
+        // re-encodes it. No decoding of its own, that stays the consumer's job.
+        self::assertSame('/administrative/assignment?page=3', $this->appRuntime->getForwardedReturnUrl());
+    }
+
+    /**
+     * Null rather than an empty string, so the url generator drops the parameter
+     * instead of emitting "r=".
+     */
+    public function testNothingIsPassedOnWithoutAReturnUrl(): void
+    {
+        $this->requestStack->push(Request::create('/administrative/assignment/detail/abc'));
+
+        self::assertNull($this->appRuntime->getForwardedReturnUrl());
+    }
+
+    public function testNothingIsPassedOnForAnEmptyReturnUrl(): void
+    {
+        $this->requestStack->push(Request::create('/administrative/assignment/detail/abc?r='));
+
+        self::assertNull($this->appRuntime->getForwardedReturnUrl());
+    }
+}