If you have a model that has a uniqueness validation using
`case_sensitive: false`, and you are testing against but do not qualify
the matcher with `case_insensitive`, then the matcher will pass
unexpectedly. Take this model for instance:
class Product < ActiveRecord::Base
validates_uniqueness_of :name, case_sensitive: false
end
Currently, the following test passes. With this commit, it will now
(correctly) fail:
describe Product do
it { is_expected.to validate_uniqueness_of(:name) }
end