Test Omniauth Facebook Callback Controllers in Devise with rspec

gistfile1.rb

require 'spec_helper'

describe Users::OauthCallbacksController, "handle facebook authentication callback" do
  
  describe "#annonymous user" do
    context "when facebook email doesn't exist in the system" do
      before(:each) do
        stub_env_for_omniauth

        get :facebook
        @user = User.where(:email => "[email protected]").first
      end

      it { @user.should_not be_nil }

      it "should create authentication with facebook id" do
        authentication = @user.authentications.where(:provider => "facebook", :uid => "1234").first
        authentication.should_not be_nil
      end

      it { should be_user_signed_in }

      it { response.should redirect_to tasks_path }
    end
    
    context "when facebook email already exist in the system" do
      before(:each) do
        stub_env_for_omniauth
        
        User.create!(:email => "[email protected]", :password => "my_secret")
        get :facebook
      end
      
      it { flash[:notice].should == "Your email [email protected] is already exist in the system. You need to sign in first."}
      
      it { response.should redirect_to new_user_session_path }
    end
  end
  
  describe "#logged in user" do
    context "when user don't have facebook authentication" do
      before(:each) do
        stub_env_for_omniauth

        user = User.create!(:email => "[email protected]", :password => "my_secret")
        sign_in user

        get :facebook
      end

      it "should add facebook authentication to current user" do
        user = User.where(:email => "[email protected]").first
        user.should_not be_nil
        fb_authentication = user.authentications.where(:provider => "facebook").first
        fb_authentication.should_not be_nil
        fb_authentication.uid.should == "1234"
      end

      it { should be_user_signed_in }

      it { response.should redirect_to authentications_path }
      
      it { flash[:notice].should == "Facebook is connected with your account."}
    end
    
    context "when user already connect with facebook" do
      before(:each) do
        stub_env_for_omniauth
        
        user = User.create!(:email => "[email protected]", :password => "my_secret")
        user.authentications.create!(:provider => "facebook", :uid => "1234")
        sign_in user

        get :facebook
      end
      
      it "should not add new facebook authentication" do
        user = User.where(:email => "[email protected]").first
        user.should_not be_nil
        fb_authentications = user.authentications.where(:provider => "facebook")
        fb_authentications.count.should == 1
      end
      
      it { should be_user_signed_in }
      
      it { flash[:notice].should == "Signed in successfully." }
      
      it { response.should redirect_to tasks_path }
      
    end
  end
  
end

def stub_env_for_omniauth
  # This a Devise specific thing for functional tests. See https://github.com/plataformatec/devise/issues/closed#issue/608
  request.env["devise.mapping"] = Devise.mappings[:user]
  env = { "omniauth.auth" => { "provider" => "facebook", "uid" => "1234", "extra" => { "user_hash" => { "email" => "[email protected]" } } } }
  @controller.stub!(:env).and_return(env)
end

Why do you stub in the ominauth.auth field when you don't stub in Devise's hash as well?
You might as well just set in and shorten the call stack. Adding to that, the information you set from https://github.com/intridea/omniauth/wiki/Integration-Testing could be taken into play here.

I agree with @jalcine.
A safer approach would be request.env["omniauth.auth"] = env["omniauth.auth"] and so the stub_env_for_omniauth will be:

def stub_env_for_omniauth
  # This a Devise specific thing for functional tests. See https://github.com/plataformatec/devise/issues/closed#issue/608
  request.env["devise.mapping"] = Devise.mappings[:user]
  env = { "omniauth.auth" => { "provider" => "facebook", "uid" => "1234", "extra" => { "user_hash" => { "email" => "[email protected]" } } } }
  request.env["omniauth.auth"] = env["omniauth.auth"]
end

It would be better to use OmniAuth::AuthHash.new in order to simulate the params; otherwise you could get errors if you accessed params in your code like request.env["omniauth.auth"].provider

def stub_env_for_omniauth
  # This a Devise specific thing for functional tests. See https://github.com/plataformatec/devise/issues/closed#issue/608
  request.env["devise.mapping"] = Devise.mappings[:user]

  request.env["omniauth.auth"] = OmniAuth::AuthHash.new({
    "provider"=>"facebook",
    "uid"=>uid,
    ...
  })
end

Great tests! I used them in my project. Thanks!

Couple of tests I'd add would be to test when user rejects facebook authentication.

Also, here's another test I added, which is not necessarily needed, but I like to have it around:

it "should alias #facebook to #auth_all" do
  expect(Users::OauthCallbacksController.instance_method(:facebook)).to eq(Users::OauthCallbacksController.instance_method(:auth_all))
end

For those who are doing request tests in Rails 7:

RSpec.describe OmniauthCallbacksController, type: :request do
  context "when admin does not exist" do
    it "should redirect admin to new session path" do
      OmniAuth.config.test_mode = true
      OmniAuth.config.mock_auth[:google_oauth2] = OmniAuth::AuthHash.new(
        provider: "google_oauth2",
        uid: "123",
        info: OmniAuth::AuthHash::InfoHash.new(email: "[email protected]", name: "jose"),
        extra: {
          raw_info: OmniAuth::AuthHash.new(email_verified: true)
        }
      )
      Rails.application.env_config["omniauth.auth"] = OmniAuth.config.mock_auth[:google_oauth2]

      get admin_google_oauth2_omniauth_callback_path

      expect(response.code).to eq("302")
      expect(response).to redirect_to(new_admin_session_path)
      expect(flash[:alert]).to eq("User not found")
    end
  end
end