记录下来lambda的用处

@required_attributes = [:member, :project,:membership_role, :membership_type]

@hash = @required_attributes.inject({}) { |memo, obj| memo[obj] = Factory(obj); memo }

hash.keys.each do |key|

    h_c = hash.clone

    h_c.delete(key)

    lambda{

      obj.create!(h_c)

    }.should raise_exception(

      ActiveRecord::RecordInvalid,

     "Validation failed: #{key.to_s.gsub(/_id/, '').capitalize.gsub(/_/, ' ')} can't be blank"

    ) 

 end