Testing an api call with Elixir/Phoenix

I'm new to Elixir and Phoenix and I'm trying to create a web service to compliment my web site. To start with, I just want to test my new data structure by importing some data from a json file. I thought I'd do this with a test. I've read through the basic guides (including the testing section), but I haven't been able to find anything on testing an api call.

From the code below, I get the following error when I run mix test:

** (ArgumentError) flash not fetched, call fetch_flash/2

This fails on the line that makes the call and returns the connection. I'm assuming that I'm using the wrong call/missing something? Is there documentation that I've missed, or can somebody point me to a good example?

Here's a snippet from my router.ex:

  scope "/", ContactsApp do
    pipe_through :browser # Use the default browser stack

    get "/", PageController, :index
    resources "/contacts", ContactsController
  end

  # Other scopes may use custom stacks.
  scope "/api", ContactsApp do
    pipe_through :api

    get "/import", ContactsController, :import
  end

For the time being, all I've done is copy the ContactsController.Create method and called it ContactsController.Import. I also copied the "creates resource and redirects when data is valid" test and used :import instead of :create