#app/models/season_storage.rb

before_validation :sanitize_inputs
...
validates :storage_id, uniqueness: { scope: :epoch }
validates :epoch, presence: true
validates :epoch, format: /A20[0-9]{2}-(spring|autumn)Z/
...
def sanitize_inputs
  storage_id.upcase!
end



#spec/models/season_storage.rb

it { is_expected.to validate_uniqueness_of(:storage_id).ignoring_case_sensitivity.scoped_to(:epoch) }

Failure/Error: it { is_expected.to validate_uniqueness_of(:storage_id).ignoring_case_sensitivity.scoped_to(:epoch) }

       Expected SeasonStorage to validate that :storage_id is unique within the
       scope of :epoch, but this could not be proved.
         After taking the given SeasonStorage, setting its :storage_id to
         ‹"dummy value"›, and saving it as the existing record, then making a
         new SeasonStorage and setting its :storage_id to ‹"dummy value"› (read
         back as ‹"DUMMY VALUE"›) as well e its :epoch to a different value,
         ‹nil›, the matcher expected the new SeasonStorage to be invalid, but
         it was valid instead.

         As indicated in the message above, :storage_id seems to be changing
         certain values as they are set, and this could have something to do
         with why this test is failing. If you or something else has overridden
         the writer method for this attribute to normalize values by changing
         their case in any way (for instance, ensuring that the attribute is
         always downcased), then try adding `ignoring_case_sensitivity` onto
         the end of the uniqueness matcher. Otherwise, you may need to write
         the test yourself, or do something different altogether.

as well e its :epoch to a different value,
‹nil›, the matcher expected the new SeasonStorage to be invalid, but
it was valid instead