TestExemplars
=============
 
This plugin is based off of Piers Cawley's post at http://www.bofh.org.uk/articles/2007/08/05/doing-the-fixture-thing.  It allows you to easily create valid ActiveRecord objects for use in testing.
 
Usage is really simple.  In your test_helper.rb or spec_helper.rb file just
require "test_exemplars"
include ExemplarBuilder
 
This provides you with the exemplify method that you can use to create an exemplar for any AR class.
 
Your best bet is to take a look at spec/test_exemplars_spec.rb to grok the usage.  Here are a couple examples though.  Assume the following ActiveRecord class:
 
  class Chicken < ActiveRecord::Base
    attr_protected :ssn
  end
 
  # Basic exemplar with attributes
  exemplify Chicken, :name => "chicken little", :age => 10
  Chicken.exemplar    => #<Chicken:0x31227f0 @attributes={"name"=>"chicken little", "ssn"=>nil, "age"=>10}, @new_record=true>
  
  # Override attributes
  exemplify Chicken, :name => "chicken little", :age => 10
  Chicken.exemplar(:name => "amazing")    => #<Chicken:0x3120374 @attributes={"name"=>"amazing", "ssn"=>nil, "age"=>10}, @new_record=true>
  
exemplify also takes an optional block.  This is useful for methods you need to call on the exemplar.  For example, attr_protected attributes can't be mass-assigned, you need to explicitly set them.  Of course you can use it for any object initialization that isn't basic hash attributes.
 
  # ssn is ignored because of attr_protected
  exemplify Chicken, :ssn => "abc123"
  Chicken.exemplar    => #<Chicken:0x31377b8 @attributes={"name"=>nil, "ssn"=>nil, "age"=>nil}, @new_record=true>
  
  # ssn is assigned in a block
  exemplify(Chicken) {|c| c.ssn = "abc123" }
  Chicken.exemplar    => #<Chicken:0x3136e1c @attributes={"name"=>nil, "ssn"=>"abc123", "age"=>nil}, @new_record=true>
  
Finally, you can automatically populate a field's value with an autoincrementing exemplar ID.
 
  # auto populate name field
  exemplify Chicken, :auto_id => :name
  Chicken.exemplar    => #<Chicken:0x311d638 @new_record=true, @attributes={"name"=>"Chicken1", "ssn"=>nil, "age"=>nil}>
  Chicken.exemplar    => #<Chicken:0x311d638 @new_record=true, @attributes={"name"=>"Chicken2", "ssn"=>nil, "age"=>nil}>
  
You can also automatically save the record with ARClass.create_exemplar and ARClass.create_exemplar!.  They're just convenience methods that build an exemplar and call #save and #save! respectively.