Definject - Unobtrusive Dependency Injector for Elixir

Hello,

I just published version 1.1 of definject. It aims to make dependency injection unobtrusive.

import Definject

definject send_welcome_email(user_id) do
  %{email: email} = Repo.get(User, user_id)

  welcome_email(to: email)
  |> Mailer.send()
end

is expanded into (simplified for understanding)

def send_welcome_email(user_id, deps \\ %{}) do
  %{email: email} = Map.get(deps, &Repo.get/2, &Repo.get/2).(User, user_id)

  welcome_email(to: email)
  |> Map.get(deps, &Mailer.send/1, &Mailer.send/1).()
end

Then, you can inject mock functions and modules in tests.

test "send_welcome_email" do
  Accounts.send_welcome_email(100, %{
    Repo => MockRepo,
    &Mailer.send/1 => fn %Email{to: "user100@gmail.com", subject: "Welcome"} ->
      Process.send(self(), :email_sent)
    end
  })

  assert_receive :email_sent
end

definject does not require you to modify function arguments or body. Instead, you just need to replace def with definject . It also allows injecting different mocks to each function. It also does not limit using :async option as mocks are contained in each test function.

You can find definject here:
https://github.com/chain-partners/definject

Thanks!