trait CacheTestTrait

trait CacheTestTrait {
    
    /**
     * Retrieves the render cache backend as a variation cache.
     *
     * This is how Drupal\Core\Render\RenderCache uses the render cache backend.
     *
     * @return \Drupal\Core\Cache\VariationCacheInterface
     *   The render cache backend as a variation cache.
     */
    protected function getRenderVariationCache() : VariationCacheInterface {
        
        /** @var \Drupal\Core\Cache\VariationCacheFactoryInterface $variation_cache_factory */
        $variation_cache_factory = \Drupal::service('variation_cache_factory');
        return $variation_cache_factory->get('render');
    }
    
    /**
     * Retrieves the default cache backend as a variation cache.
     *
     * @return \Drupal\Core\Cache\VariationCacheInterface
     *   The default cache backend as a variation cache.
     */
    protected function getDefaultVariationCache() : VariationCacheInterface {
        
        /** @var \Drupal\Core\Cache\VariationCacheFactoryInterface $variation_cache_factory */
        $variation_cache_factory = \Drupal::service('variation_cache_factory');
        return $variation_cache_factory->get('default');
    }
    
    /**
     * Verify that a given render cache entry exists with the correct cache tags.
     *
     * @param string[] $keys
     *   The render cache item keys.
     * @param array $tags
     *   An array of expected cache tags.
     * @param \Drupal\Core\Cache\CacheableDependencyInterface $cacheability
     *   The initial cacheability the item was rendered with.
     */
    protected function verifyRenderCache(array $keys, array $tags, CacheableDependencyInterface $cacheability) : void {
        $this->verifyCache($this->getRenderVariationCache(), $keys, $tags, $cacheability);
    }
    
    /**
     * Verify that a given default cache entry exists with the correct cache tags.
     *
     * @param string[] $keys
     *   The cache item keys.
     * @param array $tags
     *   An array of expected cache tags.
     * @param \Drupal\Core\Cache\CacheableDependencyInterface $cacheability
     *   The initial cacheability for the item.
     */
    protected function verifyDefaultCache(array $keys, array $tags, CacheableDependencyInterface $cacheability) : void {
        $this->verifyCache($this->getDefaultVariationCache(), $keys, $tags, $cacheability);
    }
    
    /**
     * Verify that a given cache entry exists, with the correct cache tags.
     *
     * @param \Drupal\Core\Cache\VariationCacheInterface $cache_bin
     *   The cache bin to check.
     * @param string[] $keys
     *   The cache item keys.
     * @param array $tags
     *   An array of expected cache tags.
     * @param \Drupal\Core\Cache\CacheableDependencyInterface $cacheability
     *   The initial cacheability for the item.
     */
    private function verifyCache(VariationCacheInterface $cache_bin, array $keys, array $tags, CacheableDependencyInterface $cacheability) : void {
        $cache_entry = $cache_bin->get($keys, $cacheability);
        $this->assertInstanceOf(\stdClass::class, $cache_entry);
        sort($cache_entry->tags);
        sort($tags);
        $this->assertSame($cache_entry->tags, $tags);
    }

}