Comments on http://re-factor.com/blog/2013/09/27/slow-tests-are-the-symptom-not-the-cause/

00_blog.md

I just read http://re-factor.com/blog/2013/09/27/slow-tests-are-the-symptom-not-the-cause/.

I fully agree that the testing speed can often be a result of improving the code design.

This is probably how I'd implement a similar feature in barsoom.se's apps.

I'm mostly of the opinion that you should use the right tool for each job. Integrated tests to test integration. Unit tests to test logic and message passing.

I prefer to keep things simple and avoid dependency injection until there is a need for it outside of tests.

0_code.rb

require "attr_extras" # gem

class Controller
  def add_user
    user = User.finy_by_username!(params[:username])
    mailing_list = MailingList.new("blog_list")
    AddUserToMailingList.run(user, mailing_list)
  end
end

class AddUserToMailingList
  method_object :run,
    :user, :mailing_list
    
  def run
    mailing_list.add_user(user)
    Notify.user_added_to_mailing_list(user, mailing_list)
  end
end

class MailingList
  pattr_initialize :name
  
  def add_user(user)
    # Even if User owns the mailing_list_name column it doesn't need to know about it.
    # Having a column like it in a central table like users would likely just be a
    # simplification or an optimization in our apps.
    user.update_attributes!(mailing_list_name: name)
  end
end

1_add_user_to_mailing_list_spec.rb

require "spec_helper"

# non-rails unit test, much simpler than the blog example imho.

describe AddUserToMailingList, ".run" do
  it "adds a user to a mailing list and notifies the user" do
    user = double(:user)
    mailing_list = double(:mailing_list)
    
    expect(mailing_list).to receive(:add_user).with(user)
    expect(Notify).to receive(:user_added_to_mailing_list).with(user, mailing_list)
    
    AddUserToMailingList.run(user, mailing_list)
  end
end

2_mailing_list_spec.rb

require "spec_helper"

describe "Adding users to mailing lists" do
  it "works" do
    user = create(:user)
    visit user_path(user)
    
    click_button "Add to blog list"
    
    expect(page).to have_flash("User added to blog list")
    expect(user.reload.mailing_list_name).to eq "blog_list"
  end
end