let's add a test that checks this all works concurrently, we can probably use the [Consistently](http://onsi.github.io/gomega/#consistently) feature of gomega to write the test. e.g. `Consistently(usernamesUsed).Should(Equal([]string{"user1", "user2", "user3"}))` (assuming a func usernamesUsed that does four logins at the same time and returns the usernames used in alphabetical order).