module InactiveRecord
  module Inactivation
    # Allows an ActiveRecord class to be used without any connection
    # to the database.
    # Columns must be specified thought the +attributes+ argument.
    # Attributes must be a Hash with the column name as the key and
    # either a value or a symbol representing the column type as its
    # value.
    def inactivate!(attributes)
      self.stubs(:columns).returns(guess_db_columns(attributes))
      
      # Do not save for real!
      self.class_eval do
        def transaction
          yield
        end
        
        def create
          stubs(:id).returns 1
          self.class.finds 1, attributes
          true
        end
        
        def update
          true
        end
      end      
    end
    
    private
      # Based on http://blog.jayfields.com/2007/03/rails-activerecord-unit-testing-part-ii.html
      def guess_db_columns(attributes)
        return [] if attributes.nil?
        attributes.keys.collect do |attribute|
          sql_type = case attributes[attribute]
            when Fixnum then "integer"
            when Float  then "float"
            when Time   then "time"
            when Date   then "date"
            when String then "string"
            when Symbol then attributes[attributes].to_s
            when Object then "boolean"            
          end
          ActiveRecord::ConnectionAdapters::Column.new(attribute.to_s, nil, sql_type, false)
        end
      end
  end
end