AttributeRouteDiscovery: invokable controllers with class-only #[Route] never register routes due to wrong condition

Problem/Motivation

The Change Record for PHP attribute-based route discovery documents support for invokable controllers where #[Route] is placed only on the class, with __invoke() having no attribute:

namespace Drupal\router_test\Controller;

use Drupal\Core\Controller\ControllerBase;
use Symfony\Component\Routing\Attribute\Route;

/**
 * Test controller.
 */
#[Route(
  '/test_class_attribute',
  'test_class_attribute',
  requirements: ['_access' => 'TRUE']
)]
class TestClassAttribute extends ControllerBase {

  /**
   * Provides test content.
   */
  public function __invoke() {
    return ['#markup' => 'Testing __invoke() with a Route attribute on the class'];
  }

}

This pattern does NOT work. The route is never registered.

AttributeRouteDiscovery::getRoutes() contains the following condition (line 122):

if ($collection->count() && $class->hasMethod('__invoke') === 0) {

ReflectionClass::hasMethod() returns bool. TRUE === 0 and FALSE === 0 are both FALSE under strict comparison. The condition is always FALSE, making the entire block dead code — the invokable controller fallback never executes.

Additionally, the first operand likely has the wrong polarity: the block should activate when NO routes were collected from method attributes !$collection->count(), not when some were.

Steps to reproduce

1. Create a controller with #[Route] only on the class, __invoke() with no attribute.
2. Clear caches.
3. Visit the route path — get a 404.

Proposed resolution

The correct condition should be:

if (!$collection->count() && $class->hasMethod('__invoke')) {

Note that this was already fixed incidentally in #3584793: Use PHP attributes for form route discovery, but that was committed only to main and 11.x (11.5, essentially), and without test coverage.

11.4.x needs the fix and test coverage.
main and 11.x need the test coverage only.

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet