system/Database/BaseBuilder.php
public function truncate(bool $test = false)
	{
		$table = $this->QBFrom[0];

		$sql = $this->_truncate($table);

		if ($test === true)
		{
			return $sql;
		}

		$this->resetWrite();

		return $this->db->query($sql, null, false);
	}
public function truncate(bool $test = false)
	{
		$table = $this->QBFrom[0];

		$sql = $this->_truncate($table);

		if ($test === true)
		{
			return $sql;
		}

		$this->resetWrite();

		return $this->db->query($sql, null, false);
	}
Truncate

Compiles a truncate string and runs the query
If the database does not support the truncate() command
This function maps to "DELETE FROM table"

@param boolean $test Whether we're in test mode or not.

@return boolean    TRUE on success, FALSE on failure