Rails::SessionCookie
Fast, loosely coupled requests specs for a cookie-authenticated application.
Key goals:
- how to login under any user in request tests quickly
- how to speed up capybara, selenium tests
- how to login under any user in production using rails console
Why
Probably, you might have seen a lot code like this:
# config/initializers/session_store.rb
Rails.application.config.session_store :cookie_store
# authenticating method (maybe Devise or whatever)
session[:current_user_id] = current_user.id
# somewhere in helper for request specs
def login(current_user)
post '/login', auth_data(current_user)
end
# now every request spec is calling login request
RSpec.describe 'User interface', type: :request do
let(:user) { create :user }
before do
login(user)
end
it 'shows private data' do
get '/dashboard'
end
end
In a usual user-driven application this tightly couples all request specs, which require authentication, to the login process. If it fails - everything fails. If it's not blazing fast - it slows the whole suite down.
One may move to token-based authentication, especially when having API. That's reasonable and nice. But HTTP is stateless, really we don't need to do several requests, we can think about a session cookie as a token passed in a special header!
You can easily pass headers in tests, the only hard thing is getting the cookie value. Rails may change how a state is serialized into the session cookie. It can be encrypted or not, marshalled (an old story for rails-3 legacy) or JSONed. Long story short: only rails knows how to generate cookie from data.
This gem replaces your usual process of getting session cookie with the simplest rack app utilizing 2 rails middlewares. Rails is modular, that's cool :)
Installation
# Gemfile
gem 'rails-session_cookie', group: :test
Usage in requests specs
# spec_helper.rb
require 'rails/session_cookie'
def login(current_user)
# depending on Rails version and session configuration this looks like "cookie_store_key=data--digest; path=/; HttpOnly"
raw_session_cookie = Rails::SessionCookie::App.new(current_user_id: current_user.id).session_cookie
# note, it's raw, not `<<`
cookies.merge(raw_session_cookie)
end
# ...everything else the same
Now you can cache raw_session_cookie
globally or per-thread depending on current_user_id
to get things even faster!
You can also use the raw_session_cookie
directly like this:
get "/", {}, { "HTTP_COOKIE" => raw_session_cookie }
Strictly speaking, you may cache Set-Cookie
response header from /login
URL to achieve same speed (but not coupling ;)
However, never saw this in practice, and consider caching of requests in before-phase bad. YMMV.
Advanced usage
If you need more sophisticated logic:
auth_app = proc { |env|
# do your magic
env[Rails::SessionCookie::RACK_SESSION].merge!(context)
[200, {}, []]
}
raw_session_cookie = Rails::SessionCookie::App.new(auth_app).session_cookie
Of course, you can just make use (and reuse!) of as many procs as you wish.
This effectively achieves the effect as this PR#18230, which allows session mutation in a less invasive way in regard to Rails itself ;)
Warden / Devise
Getting session cookie is dead-simple, just get the cookie this way:
raw_session_cookie = Rails::SessionCookie::WardenApp.new(user).session_cookie
Feature tests using Capybara
Get the cookie as described above according to your setup, and assign this way:
Capybara.current_session.driver.browser.set_cookie raw_session_cookie
TODO: Only tested with :rack_test
driver!
Login under any devise user in rails production
If you're in production rails console:
Rails::SessionCookie::WardenApp.new(User.last).session_cookie
If you're on remote/developer instance:
# take values from production console:
secret_key_base = Rails.application.env_config['action_dispatch.secret_key_base']
data = User.serialize_into_session(user) # [[user.id], user.encrypted_password[0,29]]
opts = Rails.application.config.session_options
# in remote rails console:
key = "warden.user.user.key" # "warden.user.#{scope}.key"
Rails::SessionCookie::App.new({ key => data }, opts).session_cookie(secret_key_base: secret_key_base)
Then inject the value inside cookies
in browser devtools.
This another friendly reminder, why you need to keep your SECRET_KEY_BASE
secure!
Benchmarks
NOTE: Sometimes devise's sign_in
is still faster than SessionCookie
(a little though),
because Warden uses an ugly hack, in my opinion,
to support test-mode authentication.
But, still, in average performance of this gem is not worse if used with user_id->cookie caching Besides, authentication becomes as transparent as possible and should increase readability if you understand HTTP session cookies principles.
$ appraisal rails-5.1-warden rspec -t performance spec/benchmarks/feature_spec.rb
# or just
$ BUNDLE_GEMFILE=gemfiles/rails_6.0_warden.gemfile bundle exec rspec
Speed using capybara in feature test
correctness of
SessionCookie
is correct
Devise Helpers
are correct
against Devise::Test::Helpers
is obviously slower separately
is not slower than devise helpers if using cache and executing multiple specs in a suite
Warming up --------------------------------------
devise sign_in
70.000 i/100ms
session cookie
70.000 i/100ms
session cookie (no cache)
62.000 i/100ms
Calculating -------------------------------------
devise sign_in
700.554 (± 5.3%) i/s - 3.500k in 5.011356s
session cookie
686.868 (± 4.7%) i/s - 3.430k in 5.005542s
session cookie (no cache)
611.439 (± 4.9%) i/s - 3.100k in 5.083986s
Comparison:
devise sign_in : 700.6 i/s
session cookie : 686.9 i/s - same-ish: difference falls within error
session cookie (no cache): 611.4 i/s - 1.15x slower
But when it comes with comparison to a simple custom authentication (see spec/support/rails_app.rb
),
this gem is several times faster! (custom action checks password, hits database, request touches the whole rails middleware stack)
$ appraisal rails-5.1-warden rspec -t performance spec/benchmarks/request_spec.rb
Speed using custom sign-in in request test
correctness of
SessionCookie
is correct
usual session controller
is correct
against custom sign in route
is faster separately without cache
Warming up --------------------------------------
custom sign in
1.000 i/100ms
session cookie
1.759k i/100ms
session cookie (no cache)
482.000 i/100ms
Calculating -------------------------------------
custom sign in
11.219 (± 0.0%) i/s - 57.000 in 5.082143s
session cookie
17.573k (± 2.0%) i/s - 87.950k in 5.006754s
session cookie (no cache)
4.714k (± 5.0%) i/s - 23.618k in 5.023448s
Comparison:
session cookie : 17573.4 i/s
session cookie (no cache): 4714.3 i/s - 3.73x slower
custom sign in : 11.2 i/s - 1566.44x slower