Step #1: Initial setup

 - Complex unrefactored Process object
 - Basic test that does 100% coverage
 - dependencies file that stubs external dependencies
 - Gemfile

samples/two_level_deep_service_objects/Gemfile

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+source 'https://rubygems.org'
+gem 'rspec'
+gem 'rspec-mocks'
+gem 'activesupport'
+gem 'activemodel'
+gem 'simplecov'

samples/two_level_deep_service_objects/Gemfile.lock

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+GEM
+  remote: https://rubygems.org/
+  specs:
+    activemodel (5.1.5)
+      activesupport (= 5.1.5)
+    activesupport (5.1.5)
+      concurrent-ruby (~> 1.0, >= 1.0.2)
+      i18n (~> 0.7)
+      minitest (~> 5.1)
+      tzinfo (~> 1.1)
+    concurrent-ruby (1.0.5)
+    diff-lcs (1.3)
+    i18n (0.9.5)
+      concurrent-ruby (~> 1.0)
+    minitest (5.11.3)
+    rspec (3.7.0)
+      rspec-core (~> 3.7.0)
+      rspec-expectations (~> 3.7.0)
+      rspec-mocks (~> 3.7.0)
+    rspec-core (3.7.1)
+      rspec-support (~> 3.7.0)
+    rspec-expectations (3.7.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.7.0)
+    rspec-mocks (3.7.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.7.0)
+    rspec-support (3.7.1)
+    thread_safe (0.3.6)
+    tzinfo (1.2.5)
+      thread_safe (~> 0.1)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  activemodel
+  activesupport
+  rspec
+  rspec-mocks
+
+BUNDLED WITH
+   1.16.1

samples/two_level_deep_service_objects/dependencies.rb

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+class StaffActionLogger
+  def initialize(*)
+    true
+  end
+
+  def log_name_change(*)
+    true
+  end
+end
+
+class User
+  include ::ActiveModel::Model
+  attr_accessor :date_of_birth
+  attr_accessor :name
+  attr_accessor :user_profile
+  attr_accessor :locale
+  attr_accessor :title
+  attr_accessor :user_option
+  attr_accessor :custom_fields
+
+  def id
+    1
+  end
+
+  def reload
+    self
+  end
+
+  def save
+    true
+  end
+
+  def custom_fields
+    {}
+  end
+
+  def self.transaction
+    yield
+  end
+end
+
+class UserProfile
+  attr_accessor :card_background
+  attr_accessor :location
+  attr_accessor :profile_background
+  attr_accessor :website
+  attr_accessor :bio_raw
+
+  def save
+    true
+  end
+
+  def website
+    'http://www.example.com'
+  end
+end
+
+class Guardian
+  attr_accessor :user
+  private
+
+  def initialize(user)
+    @user = user
+  end
+end
+
+class SiteSetting
+  cattr_accessor :sso_url
+  cattr_writer :enable_sso
+  cattr_writer :sso_overrides_bio
+
+  def self.enable_sso
+    @enable_sso || true
+  end
+
+  def self.sso_overrides_bio
+    @sso_overrides_bio || false
+  end
+end
+
+class UserUpdater
+  CATEGORY_IDS = {
+    watched_first_post_category_ids: :watching_first_post,
+    watched_category_ids: :watching,
+    tracked_category_ids: :tracking,
+    muted_category_ids: :muted
+  }
+
+  TAG_NAMES = {
+    watching_first_post_tags: :watching_first_post,
+    watched_tags: :watching,
+    tracked_tags: :tracking,
+    muted_tags: :muted
+  }
+
+  OPTION_ATTR = [
+    :email_always,
+    :mailing_list_mode,
+    :mailing_list_mode_frequency,
+    :email_digests,
+    :email_direct,
+    :email_private_messages,
+    :external_links_in_new_tab,
+    :enable_quoting,
+    :dynamic_favicon,
+    :disable_jump_reply,
+    :automatically_unpin_topics,
+    :digest_after_minutes,
+    :new_topic_duration_minutes,
+    :auto_track_topics_after_msecs,
+    :notification_level_when_replying,
+    :email_previous_replies,
+    :email_in_reply_to,
+    :like_notification_frequency,
+    :include_tl0_in_digests,
+    :theme_key,
+    :allow_private_messages,
+    :homepage_id,
+  ]
+
+  def can_grant_title?(user)
+    true
+  end
+end

samples/two_level_deep_service_objects/user_updater.rb

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+require 'active_support'
+require 'active_support/core_ext/object/blank'
+require 'active_support/core_ext/time/calculations'
+require 'active_model'
+
+require_relative 'dependencies'
+
+class UserUpdater
+  delegate :change_post_owner, to: :guardian
+
+  def update(attributes = {})
+    save_options = false
+    saved = nil
+    old_user_name = user.name.present? ? user.name : ""
+
+    user_profile = user.user_profile
+    user_profile.location = attributes.fetch(:location) { user_profile.location }
+    user_profile.dismissed_banner_key = attributes[:dismissed_banner_key] if attributes[:dismissed_banner_key].present?
+    user_profile.website = format_url(attributes.fetch(:website) { user_profile.website })
+    user_profile.profile_background = attributes.fetch(:profile_background) { user_profile.profile_background }
+    user_profile.card_background = attributes.fetch(:card_background) { user_profile.card_background }
+    if SiteSetting.enable_sso && !SiteSetting.sso_overrides_bio
+      user_profile.bio_raw = attributes.fetch(:bio_raw) { user_profile.bio_raw }
+    end
+
+    user.name = attributes.fetch(:name) { user.name }
+    user.locale = attributes.fetch(:locale) { user.locale }
+    user.date_of_birth = attributes.fetch(:date_of_birth) { user.date_of_birth }
+    if can_grant_title?(user)
+      user.title = attributes.fetch(:title) { user.title }
+    end
+
+    # special handling for theme_key cause we need to bump a sequence number
+    if attributes.key?(:theme_key) && user.user_option.theme_key != attributes[:theme_key]
+      user.user_option.theme_key_seq += 1
+    end
+
+    OPTION_ATTR.each do |attribute|
+      if attributes.key?(attribute)
+        save_options = true
+
+        if [true, false].include?(user.user_option.send(attribute))
+          val = attributes[attribute].to_s == 'true'
+          user.user_option.send("#{attribute}=", val)
+        else
+          user.user_option.send("#{attribute}=", attributes[attribute])
+        end
+      end
+    end
+
+    # automatically disable digests when mailing_list_mode is enabled
+    user.user_option.email_digests = false if user.user_option.mailing_list_mode
+
+    fields = attributes[:custom_fields]
+    if fields.present?
+      user.custom_fields = user.custom_fields.merge(fields)
+    end
+
+    User.transaction do
+      if user.user_option.save && user_profile.save && user.save
+        StaffActionLogger.new(@actor).log_name_change(
+          user.id,
+          old_user_name,
+          attributes.fetch(:name) { '' }
+        )
+
+        saved = true
+      end
+    end
+
+    saved
+  end
+
+  private
+
+  attr_reader :user, :guardian
+
+  def initialize(actor, user, guardian = Guardian.new(actor))
+    @user = user
+    @guardian = guardian
+    @actor = actor
+  end
+
+  def format_url(website)
+    return nil if website.blank?
+    website =~ /^http/ ? website : "http://#{website}"
+  end
+end

samples/two_level_deep_service_objects/user_updater_spec.rb

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+require 'simplecov'
+SimpleCov.start
+
+require_relative 'user_updater'
+
+describe UserUpdater do
+  let( :acting_user ) { User.new( name: 'Acting User', user_profile: UserProfile.new ) }
+
+  describe '#update' do
+    it 'saves user' do
+      user = User.new( name: 'Billy Bob', user_profile: UserProfile.new, user_option: spy( email_always: true ) )
+
+      updater = UserUpdater.new( acting_user, user )
+      updater.update( name: 'Jim Tom' )
+
+      expect( user.reload.name ).to eq 'Jim Tom'
+    end
+
+    it 'updates various fields' do
+      user = User.new( name: 'Billy Bob', user_profile: UserProfile.new, user_option: spy( email_always: true ) )
+      updater = UserUpdater.new(acting_user, user)
+      date_of_birth = Time.current
+
+      val = updater.update(bio_raw: 'my new bio',
+                           email_always: 'true',
+                           mailing_list_mode: true,
+                           digest_after_minutes: "45",
+                           new_topic_duration_minutes: 100,
+                           auto_track_topics_after_msecs: 101,
+                           notification_level_when_replying: 3,
+                           email_in_reply_to: false,
+                           date_of_birth: date_of_birth,
+                           theme_key: 'theme.key',
+                           custom_fields: { one: :two },
+                           allow_private_messages: false)
+
+      expect(val).to be_truthy
+
+      user.reload
+
+      expect(user.user_profile.bio_raw).to eq 'my new bio'
+    end
+
+    it "disables email_digests when enabling mailing_list_mode" do
+      user = User.new( name: 'Billy Bob', user_profile: UserProfile.new, user_option: spy( email_always: true ) )
+      updater = UserUpdater.new(acting_user, user)
+
+      val = updater.update(mailing_list_mode: true, email_digests: true)
+      expect(val).to be_truthy
+
+      user.reload
+
+      expect(user.user_option).to have_received(:mailing_list_mode=).
+                                  with( true )
+    end
+
+    context 'when sso overrides bio' do
+      it 'changes bio' do
+        SiteSetting.sso_url = "https://www.example.com/sso"
+        SiteSetting.enable_sso = true
+        SiteSetting.sso_overrides_bio = true
+
+        user = User.new( name: 'Billy Bob', user_profile: UserProfile.new, user_option: spy( email_always: true ) )
+        updater = UserUpdater.new(acting_user, user)
+
+        expect(updater.update(bio_raw: "new bio")).to be_truthy
+
+        user.reload
+        expect(user.user_profile.bio_raw).to eq 'new bio'
+      end
+    end
+
+    context 'when update fails' do
+      it 'returns false' do
+        user = User.new( name: 'Billy Bob', user_profile: UserProfile.new, user_option: spy( email_always: true ) )
+        allow(user).to receive( :save ).
+                       and_return( false )
+        updater = UserUpdater.new(acting_user, user)
+
+        expect(updater.update).to be_falsey
+      end
+    end
+  end
+end