Triage whether to add tests and refactor

[griff-rees]

This is a meta ticket to cover cases of refactoring that could ease automating of testing. These may not be viable in the time we have, but to at least keep track of these decisions for the near term versus the long term.

• python/resampling/resampling_hads.py
  • check `enforce_date_dropping.py
  • refactor python/resampling/check_calendar.py, which looks like a test as mentioned in HADs 360 day calendar conversion #32 but isn't incorporated in the pytest configuration. It does require mounting an external drive but doesn't import or call any code from python/resampling/resampling_hads.py. Shifting an equivalent of this to the tests/ folder may be helpful
  • Whether to refactor with tests
• python/debiasing/pre_processing.py
  • Checking the preprocess_data function may require refactoring
  • Whether to refactor with tests