Interestings

“respond_to :not_fun”

When using
respond_to
in a controller in Rails 3, keep in mind that the body of the action will still happen before it doesn’t find a
format
it is interested in and bails, possibly causing side effects of the action to still happen (like creating a record) but returning a 406 or other error to the client.

“Time.stub(:now) combined with waits”

Careful when stubbing
Time.now
when using, for example, steps in Cucumber that are “waiting” for things, as the clock will not move, and your tests will run until the end of time…