You were using Date.today as hash key to store rates for a specific date.
The problem is that after exporting to a string and importing again the key never returns as a Date object.
So I changed the code to use string as hash key.
I've written tests to all implementations.
fix import and export
use app id if environemnt variable set ENV['OPENEXCHANGERATES_APP_ID']
fix last commit
This pull request passes (merged 0989da9 into fc3fe5c).
This pull request passes (merged de96f1b into fc3fe5c).
Sorry, just got back from holidays.
Sounds good to me, will release a new gem version asap.