You added `strong_parameters` but forgot to test the exceptions like when you update a record that should not be updated. Also it's always nice to see some expect calls in tests:

```ruby
expect { update, :id => user, :user => { :username => 'foo' } }.to change { user.username }.by 'foo'
```

or

```ruby
user.should be_persisted
expect { put :update, :id => user, :user => attributes_for( :user ) }.to_not change { User.count }
```

Also, did you notice how I didn't use `FactoryGirl.attributes_for` and instead called `attributes_for`, that's because in `spec_helper` you can do `config.include FactoryGirl::Syntax::Methods` and you won't need to do this anymore, making specs a lot more readable.