test.rb

# Before - NoteTextStorage is
# tightly coupled
class NotePresenter
  def initialize
    @note_storage = NoteTextStorage.new
  end
  def pending_notes
    notes = @note_storage.get_all
    notes.select { |n| n.pending? }
  end
end

# After - storage is passed on
# initialization
class NotePresenter
  def initialize(storage)
    @note_storage = storage
  end
  
  def pending_notes
    notes = @note_storage.get_all
    notes.select { |n| n.pending? }
  end
end

# Dependecy Injection via dry-container
# and dry-auto_inject
class NotePresenter
  include AutoInject['note_storage']
  def pending_notes
    notes = note_storage.get_all
    notes.select { |n| n.pending? }
  end
end

dependency_container = Dry::Container.new
dependency_container.register('note_storage', -> { NoteTextStorage.new })
AutoInject = Dry::AutoInject(dependency_container)

dependency_container = Dry::Container.new
dependency_container.register('note_storage', -> { TestStorage.new })
AutoInject = Dry::AutoInject(dependency_container)