TestDiscoveryCacheContext.php

<?php

namespace Drupal\simpletest\Cache\Context;

use Drupal\Core\Cache\CacheableMetadata;
use Drupal\Core\Cache\Context\CacheContextInterface;
use Drupal\Core\PrivateKey;
use Drupal\Core\Site\Settings;
use Drupal\simpletest\TestDiscovery;

/**
 * Defines the TestDiscoveryCacheContext service.
 *
 * Cache context ID: 'test_discovery'.
 */
class TestDiscoveryCacheContext implements CacheContextInterface {
    
    /**
     * The test discovery service.
     *
     * @var \Drupal\simpletest\TestDiscovery
     */
    protected $testDiscovery;
    
    /**
     * The private key service.
     *
     * @var \Drupal\Core\PrivateKey
     */
    protected $privateKey;
    
    /**
     * The hash of discovered test information.
     *
     * Services should not be stateful, but we only keep this information per
     * request. That way we don't perform a file scan every time we need this
     * hash. The test scan results are unlikely to change during the request.
     *
     * @var string
     */
    protected $hash;
    
    /**
     * Construct a test discovery cache context.
     *
     * @param \Drupal\simpletest\TestDiscovery $test_discovery
     *   The test discovery service.
     * @param \Drupal\Core\PrivateKey $private_key
     *   The private key service.
     */
    public function __construct(TestDiscovery $test_discovery, PrivateKey $private_key) {
        $this->testDiscovery = $test_discovery;
        $this->privateKey = $private_key;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function getLabel() {
        return t('Test discovery');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getContext() {
        if (empty($this->hash)) {
            $tests = $this->testDiscovery
                ->getTestClasses();
            $this->hash = $this->hash(serialize($tests));
        }
        return $this->hash;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheableMetadata() {
        return new CacheableMetadata();
    }
    
    /**
     * Hashes the given string.
     *
     * @param string $identifier
     *   The string to be hashed.
     *
     * @return string
     *   The hash.
     */
    protected function hash($identifier) {
        return hash('sha256', $this->privateKey
            ->get() . Settings::getHashSalt() . $identifier);
    }

}