Testing Elixir

Testing Singleton Resources

It’s quite common in Elixir and Erlang applications to have singleton resources. A singleton resource exists in your application as a single and unique unit. For example, a process with a globally registered name is a singleton resource, since no other process with that same name can exist in the system at the same time. That example is a bit oversimplified.

A more common and realistic example is a process that does something that should be done by at most one process at a time—for example, a process that needs exclusive access to a file on the file system or a process that periodically notifies users via SMS that it’s going to rain soon. See where we’re going with the latter? If we have more than one of this kind ...