During August 2025, Sigurd Holsen enhanced the reliability and maintainability of time series migration tests in the cognitedata/toolkit repository. He focused on improving the TestMigrateTimeSeriesCommand by removing time.sleep dependencies, fetching migrated time series using instance_id, and leveraging Python’s csv.writer for clearer CSV output. This approach enabled more deterministic and straightforward assertions on migrated data points, streamlining integration testing and accelerating CI feedback. Sigurd’s work demonstrated effective use of Python, CSV handling, and command line interface skills to address test flakiness and improve test data management, resulting in a more robust and maintainable testing framework for data migration workflows.