[6.x] Fix CP Nav active state when trailing slashes are enforced (#14363)

Author: duncanmcclean

src/CP/Navigation/NavItem.php

@@ -149,6 +149,7 @@ protected function generateActivePatternForCpUrl($url)
         $cpUrl = url(config('statamic.cp.route')).'/';
 
         $relativeUrl = str_replace($cpUrl, '', URL::removeQueryAndFragment($url));
+        $relativeUrl = rtrim($relativeUrl, '/');
 
         return $relativeUrl.'(/(.*)?|$)';
     }

tests/CP/Navigation/ActiveNavItemTest.php

@@ -12,6 +12,7 @@
 use Statamic\Facades;
 use Statamic\Facades\Blink;
 use Statamic\Facades\CP\Nav;
+use Statamic\Facades\URL;
 use Statamic\Facades\User;
 use Tests\FakesRoles;
 use Tests\PreventSavingStacheItemsToDisk;
@@ -35,6 +36,13 @@ public function setUp(): void
         Facades\Form::shouldReceive('all')->andReturn(collect());
     }
 
+    public function tearDown(): void
+    {
+        URL::enforceTrailingSlashes(false);
+
+        parent::tearDown();
+    }
+
     protected function resolveApplicationConfiguration($app)
     {
         parent::resolveApplicationConfiguration($app);
@@ -408,6 +416,34 @@ public function it_resolves_extension_children_closure_and_can_check_when_parent
         $this->assertTrue($this->getItemByDisplay($seoPro->children(), 'Section Defaults')->isActive());
     }
 
+    #[Test]
+    public function it_properly_handles_is_active_checks_when_trailing_slashes_are_enforced()
+    {
+        URL::enforceTrailingSlashes();
+
+        Nav::clearCachedUrls();
+
+        $parent = Nav::create('parent')
+            ->section('test')
+            ->url('http://localhost/cp/parent')
+            ->children([
+                $hello = Nav::create('hello')->url('http://localhost/cp/hello'),
+                $world = Nav::create('world')->url('http://localhost/cp/world'),
+            ]);
+
+        // Test active status with trailing slash in request URL
+        Request::swap(Request::create('http://localhost/cp/hello/'));
+        $this->assertTrue($parent->isActive());
+        $this->assertTrue($hello->isActive());
+        $this->assertFalse($world->isActive());
+
+        // Test active status on descendant with trailing slash
+        Request::swap(Request::create('http://localhost/cp/hello/nested/path/'));
+        $this->assertTrue($parent->isActive());
+        $this->assertTrue($hello->isActive());
+        $this->assertFalse($world->isActive());
+    }
+
     #[Test]
     public function it_properly_handles_various_edge_cases_when_checking_is_active_on_descendants_of_nav_children()
     {