Mocking a child object

duration_rule.rb

class DurationRule < ActiveRecord::Base
  include RuleMixin

  validate :min_or_max_set
  validate :min_less_than_max

  def satisfied?
    true if event.time_span.duration > min_duration

    false
  end

  def min_or_max_set
    unless self.min_duration || self.max_duration
      errors.add(:base, "Minimum or maximum duration must be set")
    end
  end

  def min_less_than_max
    if self.min_duration && self.max_duration
      errors.add(:min_duration, "must be less than 'at most'") if self.min_duration > self.max_duration
    end
  end
end

duration_rule_test.rb

require 'test_helper'

class DurationRuleTest < ActiveSupport::TestCase
  should have_one(:event).through(:rule_assignment)

  should "not save if no minimum or maximum duration set" do
    refute DurationRule.new.save
  end

  should "save if minimum duration set" do
    assert DurationRule.new(:min_duration => 10).save
  end

  should "save if maximum duration set" do
    assert DurationRule.new(:max_duration => 10).save
  end

  should "save if minimum and maximum duration set" do
    assert DurationRule.new(:min_duration => 10, :max_duration => 10).save
  end

  should "not save if maximum duration is less than minimum duration" do
    refute DurationRule.new(:min_duration => 20, :max_duration => 10).save
  end

  context "with a DurationRule assigned to an Event" do
    setup do
      @event = FactoryGirl.create(:event)
      @rule = DurationRule.create(:min_duration => 10)
      @rule_assignment = RuleAssignment.create(:event => @event, :rule => @rule)
    end

    should "be satisfied if meets minimum duration" do
      @event.time_span = mock(:time_span)
      @rule.min_duration = 50

      assert_equal true, @rule.satisfied?
    end
  end
end

event.rb

class Event < ActiveRecord::Base
  has_many :convention_resourceables, :as => :resourceable
  has_many :conventions, :through => :convention_resourceables
  has_one :time_span, :as => :time_spanable

  has_many :rule_assignments, :dependent => :destroy
  has_many :rules, :through => :rule_assignments
  has_many :be_scheduled_rules, :through => :rule_assignments, :source_type => 'BeScheduledRule'

  def rules
    rule_assignments.collect {|rule_assignment| rule_assignment.rule}
  end

  def scheduled?
    return true if time_span
    false
  end
end

rule_mixin.rb

module RuleMixin

  def self.included(base)
    base.has_one :rule_assignment, :as => :rule, :dependent => :destroy
    base.has_one :event, :through => :rule_assignment
  end

  def satisfied?
    false
  end

  def violated?
    !satisfied?
  end

  def activity
    rule_assignment.activity
  end

  def message
    ""
  end

end

Trace

ActiveRecord::AssociationTypeMismatch: TimeSpan(#38173560) expected, got Mocha::Mock(#20908400)
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.2/lib/active_record/associations/association.rb:204:in `raise_on_type_mismatch'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.2/lib/active_record/associations/has_one_association.rb:8:in `replace'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.2/lib/active_record/associations/singular_association.rb:17:in `writer'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.2/lib/active_record/associations/builder/association.rb:51:in `block in define_writers'
/home/lsimons/RubymineProjects/connie/test/unit/duration_rule_test.rb:34:in `block (2 levels) in <class:DurationRuleTest>'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/shoulda-context-1.0.0/lib/shoulda/context/context.rb:398:in `call'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/shoulda-context-1.0.0/lib/shoulda/context/context.rb:398:in `block in create_test_from_should_hash'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/mocha-0.10.5/lib/mocha/integration/mini_test/version_230_to_262.rb:28:in `run'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.2.2/lib/active_support/testing/setup_and_teardown.rb:35:in `block in run'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.2.2/lib/active_support/callbacks.rb:425:in `_run__2111581593048511830__setup__3309778514694696817__callbacks'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.2.2/lib/active_support/callbacks.rb:405:in `__run_callback'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.2.2/lib/active_support/callbacks.rb:385:in `_run_setup_callbacks'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.2.2/lib/active_support/callbacks.rb:81:in `run_callbacks'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.2.2/lib/active_support/testing/setup_and_teardown.rb:34:in `run'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-reporters-0.5.1/lib/minitest/test_runner.rb:21:in `run'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-reporters-0.5.1/lib/minitest/suite_runner.rb:68:in `_run_test'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-reporters-0.5.1/lib/minitest/suite_runner.rb:55:in `block in _run_suite'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-reporters-0.5.1/lib/minitest/suite_runner.rb:55:in `each'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-reporters-0.5.1/lib/minitest/suite_runner.rb:55:in `_run_suite'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-reporters-0.5.1/lib/minitest/suite_runner.rb:40:in `block (2 levels) in _run_anything'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-reporters-0.5.1/lib/minitest/suite_runner.rb:40:in `each'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-reporters-0.5.1/lib/minitest/suite_runner.rb:40:in `block in _run_anything'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-reporters-0.5.1/lib/minitest/suite_runner.rb:106:in `fix_sync'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-reporters-0.5.1/lib/minitest/suite_runner.rb:39:in `_run_anything'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-2.11.4/lib/minitest/unit.rb:952:in `run_tests'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-2.11.4/lib/minitest/unit.rb:939:in `block in _run'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-2.11.4/lib/minitest/unit.rb:938:in `each'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-2.11.4/lib/minitest/unit.rb:938:in `_run'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-2.11.4/lib/minitest/unit.rb:927:in `run'
/home/lsimons/.rvm/gems/ruby-1.9.2-p290/gems/minitest-2.11.4/lib/minitest/unit.rb:695:in `block in autorun'