Issue #3101664 by bvoynick, claudiu.cristea, Matroskeen, Josh Waihi,...

      return implode(',', $this->user->getRoles());

    }

    else {

      return (in_array($role, $this->user->getRoles()) ? '0' : '1');

      return (in_array($role, $this->user->getRoles()) ? 'true' : 'false');

    }

  }

<?php

namespace Drupal\Tests\Core\Cache\Context;

use Drupal\Core\Cache\Context\UserRolesCacheContext;

use Drupal\Core\Session\AccountInterface;

use Drupal\Tests\UnitTestCase;

/**

 * @coversDefaultClass \Drupal\Core\Cache\Context\UserRolesCacheContext

 * @group Cache

 */

class UserRolesCacheContextTest extends UnitTestCase {

  /**

   * @covers ::getContext

   */

  public function testCalculatedRole(): void {

    $current_user = $this->prophesize(AccountInterface::class);

    // Ensure the ID is not 1. This cache context gives user 1 a special superuser value.

    $current_user->id()->willReturn(2);

    $current_user->getRoles()->willReturn(['role1', 'role2']);

    $cache_context = new UserRolesCacheContext($current_user->reveal());

    $this->assertSame('true', $cache_context->getContext('role1'));

    $this->assertSame('false', $cache_context->getContext('role-not-held'));

  }

}