class TestSqlBase

class TestSqlBase extends SqlBase {
    
    /**
     * The query to execute.
     *
     * @var \Drupal\Core\Database\Query\SelectInterface
     */
    protected $query;
    
    /**
     * Overrides the constructor so we can create one easily.
     *
     * @param array $configuration
     *   The plugin instance configuration.
     * @param \Drupal\migrate\Plugin\MigrationInterface $migration
     *   (optional) The migration being run.
     */
    public function __construct(array $configuration = [], MigrationInterface $migration = NULL) {
        parent::__construct($configuration, 'sql_base', [], $migration, \Drupal::state());
    }
    
    /**
     * Gets the database without caching it.
     */
    public function getDatabase() {
        $this->database = NULL;
        return parent::getDatabase();
    }
    
    /**
     * Allows us to set the configuration from a test.
     *
     * @param array $config
     *   The config array.
     */
    public function setConfiguration($config) {
        $this->configuration = $config;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getIds() {
    }
    
    /**
     * {@inheritdoc}
     */
    public function fields() {
    }
    
    /**
     * {@inheritdoc}
     */
    public function query() {
        return $this->query;
    }
    
    /**
     * Sets the query to execute.
     *
     * @param \Drupal\Core\Database\Query\SelectInterface $query
     *   The query to execute.
     */
    public function setQuery(SelectInterface $query) {
        $this->query = $query;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getHighWaterStorage() {
        return parent::getHighWaterStorage();
    }

}