class RSpecJUnitFormatter

def swap_rspec_configuration(key, value)

correctly, but also that the original state is definitely restored.
configuration. This method makes sure configuration gets swapped in
the way it cascades defaults, command line arguments, and user
rspec makes it really difficult to swap in configuration temporarily due to 
def swap_rspec_configuration(key, value)
  unset = Object.new
  force = RSpec.configuration.send(:value_for, key) { unset }
  if unset.equal?(force)
    previous = RSpec.configuration.send(key)
    RSpec.configuration.send(:"#{key}=", value)
  else
    RSpec.configuration.force({key => value})
  end
  yield
ensure
  if unset.equal?(force)
    RSpec.configuration.send(:"#{key}=", previous)
  else
    RSpec.configuration.force({key => force})
  end
end