RSpec extension: matcher to test attr_protected

protect_attributes_matcher.rb

# Refactored from: http://snippets.dzone.com/posts/show/4712
Spec::Matchers.define :protect_attributes do |*attributes|
  match do |target|    
    calculate_protected_methods(target)
    perform_check(attributes)
  end
  
  failure_message_for_should do |target|
    "expected #{@failed_attribute} to be protected"
  end
  
  failure_message_for_should_not do |target|
    "expected #{@failed_attribute} to not be protected"
  end
  
  description do
    "protect attributes #{attributes.join(", ")}"
  end
  
  def calculate_protected_methods(target)
    read = proc {|var| target.instance_eval { self.class.read_inheritable_attribute(var) } }
    accessible = read.call(:attr_accessible)
    protekted = read.call(:attr_protected)
    all = target.class.column_names.map(&:to_sym)
        
    @protected = []
    @protected = protekted.to_a.map!(&:to_sym) if protekted
    @protected = all - accessible.to_a.map!(&:to_sym) if @accessible
    
    @accessible = (all - @protected).to_a
  end
  
  def perform_check(attributes)
    failed_attributes = (attributes & @accessible)
    @failed_attribute = failed_attributes.first
    failed_attributes.empty?
  end
end