def save_report(self, file_path):
        """Write coveralls report to file."""
        try:
            report = self.create_report()
        except coverage.CoverageException as e:
            log.error('Failure to gather coverage:', exc_info=e)
        else:
            with open(file_path, 'w') as report_file:
                report_file.write(report)
Write coveralls report to file.