integration_helper.rb

require_relative 'test_helper'

require 'rack/test'
require 'minitest/autorun'
require 'capybara'
require 'capybara/dsl'
include Capybara::DSL

def app
  MyApp::Server
end

Capybara.app = app

OmniAuth.config.test_mode = true

OmniAuth.config.mock_auth[:github] = OmniAuth::AuthHash.new({
  :provider => 'github',
  :uid => '123545',
  :nickname => 'garethrees'
  # etc.
})

sign_in_spec.rb

require_relative '../integration_helper'

describe 'A User can sign in' do
  
  include Rack::Test::Methods

  before do 
    request.env["omniauth.auth"] = OmniAuth.config.mock_auth[:github] 
  end

  specify 'guest user can create an account' do
    visit '/'
    click_link 'Sign in with GitHub'
    assert # can find user
  end

end

test_helper.rb

ENV['RACK_ENV'] = 'test'

require_relative '../lib/myapp'