Emails need to be unique. This would fail if you were to create two users using FactoryGirl because they would have the same email. Same goes for `username` once you add the unique index there.

We can fix this by using [sequences](https://github.com/thoughtbot/factory_girl/blob/master/GETTING_STARTED.md#sequences)

Example:

```ruby
sequence(:email) { |n| "gene#{n}@kiss.com" }
```

The first user created will have the email "gene1@kiss.com", the second "gene2@kiss.com" and so on.