This adapter should be used in your test environments. It requires no configuration.

config :my_app, MyApp.Mailer,
  adapter: Courier.Adapters.Test,
  interval: 0,                     # Will force the poller to send instantly
  delivery_timeout: 1_000_000      # Useful if you want to use IEx.pry

It is most suitable to use during acceptance tests. Because all messages are sent asynchronously via Courier.Scheduler you must block on their delivery. We can do this using assert_receive/2

post(conn, "/sign-up", data)
assert_receive {:delivered, message}, 100

It is suggested to pass a small timeout value.

All message delivery will be delegated to Courier.Adapters.Agent for storage. If you need to access to the messages you can do so at any time

Courier.Adapters.Test.messages()

In fact, any of the functions available in Courier.Adapters.Agent are available.