active_record_spec_helper.rb

require 'active_record'
require 'jc-validates_timeliness'
require 'shoulda/matchers'
                                                                                                      
Dir[File.dirname(__FILE__) + "/support/**/*.rb"].each {|f| require f}                                 
  
connection_info = YAML.load_file("config/database.yml")["test"]                                       
ActiveRecord::Base.establish_connection(connection_info)
    
RSpec.configure do |config|                                                                           
  config.around do |example|
    ActiveRecord::Base.transaction do                                                                 
      example.run
      raise ActiveRecord::Rollback                                                                    
    end
  end
end

stopwatch.rb

class Stopwatch < ActiveRecord::Base
  attr_accessible :label, :premedication_configuration_id, :starts_automatically

  belongs_to :premedication_configuration
  has_many :premedication_stopwatches

  before_create :set_default_label 
  before_destroy proc { return false }, if: :mandatory?

  validates :label, presence: true, on: :update
  validates :label, length: { maximum: 30 }
  validates :premedication_configuration, presence: true

  delegate :future?, to: :premedication_configuration

  scope :named, -> (term) { where(name: term) }

  def to_s
    label
  end 

  def mandatory?
    name.present?
  end 

private
  def set_default_label
    self.label ||= I18n.t('new_stopwatch')
  end 
end

stopwatch_spec.rb

require 'active_record_spec_helper'
require 'models/stopwatch'
require 'models/premedication_configuration'
                                                                                                      
describe Stopwatch do
# the stopwatch setup is odd, because I want to mock the associated premedication_configuration
  let(:stopwatch) {
    stopwatch = Stopwatch.new(label: 'Test')
    # stopwatch.premedication_configuration = mock_model(PremedicationConfiguration)
    # --> mock_model fails with: 
    # Failure/Error: stopwatch.premedication_configuration = mock_model(PremedicationConfiguration)
    #     NoMethodError:
    #   undefined method `mock_model' for #<RSpec::Core::ExampleGroup::Nested_1::Nested_1:0x00000002be82d0>
    stopwatch.premedication_configuration = PremedicationConfiguration.new
    stopwatch
  } 
  subject { stopwatch }
      
  describe "accessible attributes" do
    it { expect(subject).to allow_mass_assignment_of(:label) }
    it { expect(subject).to allow_mass_assignment_of(:premedication_configuration_id) }
    it { expect(subject).to allow_mass_assignment_of(:starts_automatically) }
    it { expect(subject).not_to allow_mass_assignment_of(:name) }
  end

  describe "validations" do
    it { expect(subject).to be_valid }
    it { expect(subject).to validate_presence_of(:label).on(:update) }
    it { expect(subject).to ensure_length_of(:label).is_at_most(30) }
    it { expect(subject).to validate_presence_of(:premedication_configuration) }
  end
end