def _choose_filename(self) -> None:
        """Set self._filename based on inited attributes."""
        if self._no_disk:
            self._filename = ":memory:"
        else:
            self._filename = self._basename
            suffix = filename_suffix(self._suffix)
            if suffix:
                self._filename += f".{suffix}"
Set self._filename based on inited attributes.
coverage/sqldata.py