class TestSelection

class TestSelection extends DefaultSelection {
    
    /**
     * The condition type.
     *
     * @var string
     */
    protected $conditionType;
    
    /**
     * Whether to set the condition for reusable or non-reusable blocks.
     *
     * @var bool
     */
    protected $isReusable;
    
    /**
     * Sets the test mode.
     *
     * @param string $condition_type
     *   The condition type.
     * @param bool $is_reusable
     *   Whether to set the condition for reusable or non-reusable blocks.
     */
    public function setTestMode($condition_type = NULL, $is_reusable = NULL) {
        $this->conditionType = $condition_type;
        $this->isReusable = $is_reusable;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function buildEntityQuery($match = NULL, $match_operator = 'CONTAINS') {
        $query = parent::buildEntityQuery($match, $match_operator);
        if ($this->conditionType) {
            
            /** @var \Drupal\Core\Database\Query\ConditionInterface $add_condition */
            $add_condition = NULL;
            switch ($this->conditionType) {
                case 'base':
                    $add_condition = $query;
                    break;
                case 'group':
                    $group = $query->andConditionGroup()
                        ->exists('type');
                    $add_condition = $group;
                    $query->condition($group);
                    break;
                case "nested_group":
                    $query->exists('type');
                    $sub_group = $query->andConditionGroup()
                        ->exists('type');
                    $add_condition = $sub_group;
                    $group = $query->andConditionGroup()
                        ->exists('type')
                        ->condition($sub_group);
                    $query->condition($group);
                    break;
            }
            if ($this->isReusable) {
                $add_condition->condition('reusable', 1);
            }
            else {
                $add_condition->condition('reusable', 0);
            }
        }
        return $query;
    }

}