Okay – as I understand it you're asking for what the best practices are for testing a Rails model. The fact that it's auto-generated by Devise is largely irrelevant.
The first thing I would consider here is what it is that you're actually testing – most of your code here is testing the underlying implementation of Devise. That shouldn't be the responsibility of your application's test suite – the library has a bunch of tests that should test that for you.
The only real useful tests here, IMO, are the association tests (which look like they come from
shoulda-matchers). The rest of the assertions here are testing Devise-specific code, which is tightly coupling your test suite to a 3rd-party library – that's only going to put you in a world of pain further down the line.