post.rb

class Post < ActiveRecord::Base


	  
	class << self
		alias_method :find_standard, :find
	end
	validates_presence_of :publish_from, :publish_to
	before_create :validates_time
	
	def validates_time
	   [:publish_from, :publish_to].each do |attr|
		 errors.add(attr, 'should be ActiveSupport::TimeWithZone') unless self.send(attr).is_a?(ActiveSupport::TimeWithZone) 
	   end
	   raise 'blaad' unless errors.empty?
	   
	 end
	
	def self.find(*args)
		now=Time.now
		with_scope(:find=>{ :conditions=> ["publish_from < ? and publish_to > ?", now, now] }) do
		  self.find_standard(*args)
		end
	end

	def self.between(hash, *args)
		with_scope(:find=>{ :conditions=> ["publish_from < ? and publish_to < ? and publish_to > ?", hash[:from].utc, hash[:to].utc, hash[:from].utc] }) do
		  self.find_standard(*args)
		end
	end
	
	def self.in_date(time, *args)
		with_scope(:find=>{ :conditions=> ["publish_from < ? and publish_to < ?", time.utc, time.utc] }) do
		  self.find_standard(*args)
		end
	end

end

post_spec.rb

require File.expand_path(File.dirname(__FILE__) + '/../spec_helper')



describe Post do
    fixtures :posts
  before(:each) do
    @valid_attributes = {
    :title => 'test post 4',
    :publish_from => Time.now + 2.hours,
    :publish_to => Time.now + 3.hours,
    }
    @invalid_attributes_1 = {
    :title => 'test post 4',
    :publish_from => Time.now + 3.hours
    }
    @invalid_attributes_2 = {
    :title => 'test post 4',
    :publish_from => 2,
    :publish_from => '11'
    }
  end

it "should create a new instance given valid attributes" do
  Post.create!(@valid_attributes).should be_kind_of(Post)
end

it "should return validation of presence error " do
  lambda { Post.create!(@invalid_attributes_1) }.should raise_error
end
it "should return data type mismatch error" do
  lambda { Post.create!(@invalid_attributes_2) }.should raise_error
end

describe "functional tests of" do
    describe "searching with :find method" do

      it "should return post with id 1" do 
        current_time = Time.parse('2008-12-10 01:28:00 CET').utc
        Time.stub!(:now).and_return(current_time)
        posts=Post.find(:all)
        posts.size.should == 1
        posts.first.id.should == 1
      end
      
      it "should return post with id 2" do 
        current_time = Time.parse('2008-12-10 02:28:00 CET').utc
        Time.stub!(:now).and_return(current_time)
        posts=Post.find(:all)
        posts.size.should == 1
        posts.first.id.should == 2
      end

      it "should return no posts" do 
        current_time = Time.parse('2008-12-10 03:28:00 CET').utc
        Time.stub!(:now).and_return(current_time)
        posts=Post.find(:all)
        posts.size.should == 0
      end
      
    end
    describe "searching with :between method" do
        it "should return posts with id 1 and 2" do
            
        end
        
    end
end

    describe "behavioral tests of" do
        describe "standard lists posts in category" do
            it "should find all published posts in current category" do
                
            end
        end
    end
  
end