Traject extract_marc default value

emtest.rb

require 'traject'
include Traject::Macros::Marc21

r = MARC::Record.new
r << MARC::ControlField.new('001', '12345')
r << MARC::DataField.new('245', ' ', ' ', ['a', 'My Title'])


context = Traject::Indexer::Context.new

acc1 = []
em1 = extract_marc('245a:999b', :default=>'Default Value')
em1.call(r,acc1, context) #=> acc1 == ['My Title']

acc2 = []
em2 = extract_marc('999b',      :default=>'Default Value')
em2.call(r,acc2,context) #=> acc2 == ['Default Value']

acc3 = []
em3 = extract_marc('999b', :default => nil)
em3.call(r,acc3,context) #=> acc3 == [], not [nil]

class NullObject
  def nil? 
    true
  end
end

acc4 = []
nobj = NullObject.new
em4 =  extract_marc('999b', :default => nobj)
em4.call(r,acc4,context) #=> acc4 == [nobj]