Refacto Test of invalid Country exception
Previously used a to be_valid
matcher.
Turns out that it's not the best way to test this behaviour beacause when it fails it tells you nothing about the actual behaviour under test. A real problem is also that it's testing every single validation at once on your model.
Instead we should just setup the model with valid or invalid data (arrange) and call #valid?
to trigger the validations (act) and then write expectations based on the ActiveModel::Errors API provided by rails (assert).