We can't just "swap" those model properties, as that sets instance vars
on the classes that get reverted to their "previous" value, which ends
up leaving the instance vars set as `nil`. However, our logic for those
model/class properties actually checks for `defined?` as a way to
override them, and delegates up to `Devise` global config if they are
not defined, so leaving instance vars back with `nil` values isn't
enough, we need to actually remove them.
This introduces a new test helper specifically for overriding those
model configs so that we can do proper cleanup.
* Fix missing validations on Signup
This commit fixes issue
https://github.com/plataformatec/devise/issues/4673
This removes `validate: false` from saving a record when `Trackable` is
in use.
* Add test case
* Add mongoid model
Depending on the test order, there might a moment when a test reloads the I18n
backend and another tries to store a translation, but since the backend wasn't
re-initialized the custom translations would be overriden when i18n loads the
translations from the en.yml file.
