Add TypeScript alternative

require "scientist"

class MyWidget
  def allows?(user)
    experiment = Scientist::Default.new "widget-permissions"
    experiment.use { model.check_user?(user).valid? } # old way
    experiment.try { user.can?(:read, model) } # new way

    experiment.run
  end
end

require "scientist"

class MyWidget
  include Scientist

  def allows?(user)
    science "widget-permissions" do |experiment|
      experiment.use { model.check_user(user).valid? } # old way
      experiment.try { user.can?(:read, model) } # new way
    end # returns the control value
  end
end

require "scientist/experiment"

class MyExperiment
  include Scientist::Experiment

  attr_accessor :name

  def initialize(name)
    @name = name
  end

  def enabled?
    # see "Ramping up experiments" below
    true
  end

  def raised(operation, error)
    # see "In a Scientist callback" below
    p "Operation '#{operation}' failed with error '#{error.inspect}'"
    super # will re-raise
  end

  def publish(result)
    # see "Publishing results" below
    p result
  end
end

class MyWidget
  include Scientist

  def users
    science "users" do |e|
      e.use { User.all }         # returns User instances
      e.try { UserService.list } # returns UserService::User instances

      e.compare do |control, candidate|
        control.map(&:login) == candidate.map(&:login)
      end
    end
  end
end

science "widget-permissions" do |e|
  e.context :user => user

  e.use { model.check_user(user).valid? }
  e.try { user.can?(:read, model) }
end

class MyWidget
  include Scientist

  def allows?(user)
    science "widget-permissions" do |e|
      e.context :user => user

      e.use { model.check_user(user).valid? }
      e.try { user.can?(:read, model) }
    end
  end

  def destroy
    science "widget-destruction" do |e|
      e.use { old_scary_destroy }
      e.try { new_safe_destroy }
    end
  end

  def default_scientist_context
    { :widget => self }
  end
end

# Code under test modifies this in-place. We want to copy it for the
# candidate code, but only when needed:
value_for_original_code = big_object
value_for_new_code      = nil

science "expensive-but-worthwhile" do |e|
  e.before_run do
    value_for_new_code = big_object.deep_copy
  end
  e.use { original_code(value_for_original_code) }
  e.try { new_code(value_for_new_code) }
end

class MyWidget
  include Scientist

  def users
    science "users" do |e|
      e.use { User.all }
      e.try { UserService.list }

      e.clean do |value|
        value.map(&:login).sort
      end
    end
  end
end

class MyExperiment
  include Scientist::Experiment

  # ...

  def publish(result)
    result.control.value         # [<User alice>, <User bob>, <User carol>]
    result.control.cleaned_value # ["alice", "bob", "carol"]
  end
end

def admin?(user)
  science "widget-permissions" do |e|
    e.use { model.check_user(user).admin? }
    e.try { user.can?(:admin, model) }

    e.ignore { user.staff? } # user is staff, always an admin in the new system
    e.ignore do |control, candidate|
      # new system doesn't handle unconfirmed users yet:
      control &&!candidate &&!user.confirmed_email?
    end
  end
end