Faraday, Minitest, and VCR

client.rb

# frozen_string_literal: true
require "faraday"
require "faraday/retry"
require "httpx/adapters/faraday"

module App
  class Client
    def connection
      Faraday.new(url) do |f|
        # https://github.com/lostisland/faraday-retry#usage
        # Retry transient failures
        # By default, it retries 2 times and handles only timeout exceptions
        f.request :retry

        # https://lostisland.github.io/faraday/middleware/authentication
        # Automatically add an Authorization header to your requests
        f.request :authorization, "Bearer", -> { auth_token }

        f.request :json # encode req bodies as JSON and automatically set the Content-Type header
        f.response :json # decode response bodies as JSON

        # https://lostisland.github.io/faraday/middleware/raise-error
        # If an HTTP response returns with a 4xx or 5xx status code
        # the RaiseError middleware raises a Faraday::Error exception
        f.response :raise_error

        # https://gitlab.com/os85/httpx#what-makes-it-the-best-ruby-http-client
        # https://os85.gitlab.io/httpx/
        # https://os85.gitlab.io/httpx/wiki/home.html
        f.adapter :httpx
      end
    end

    private

    def auth_token
      ENV["AUTH_TOKEN"]
    end

    def url
      "https://example.com"
    end
  end
end

resource.rb

# frozen_string_literal: true

module App
  class Resource
    attr_reader :connection

    def initialize(connection: Client.new.connection)
      @connection = connection
    end

    def get(id:)
      connection.get("/resources/#{id}")
    end
  end
end

test_client.rb

# frozen_string_literal: true

require "test_helper"

class TestAppResource < Minitest::Test
  def setup
    @resource = App::Resource.new
  end

  def test_get
    VCR.use_cassette("test_get") do
      id = 1
      response = @resource.get(id: id)
      assert_equal id, response.body["id"]
    end
  end
end

test_helper.rb

# frozen_string_literal: true

$LOAD_PATH.unshift File.expand_path("../lib", __dir__)
require "app"
require "minitest/autorun"
require "vcr"

VCR.configure do |c|
  c.cassette_library_dir = "test/vcr"
  c.hook_into :faraday
end