class Shoulda::Matchers::ActionController::SetSessionOrFlashMatcher

def to(expected_value = nil, &block)
  if block
    unless context_set?
      message = 'When specifying a value as a block, a context must be'\
        ' specified beforehand,'\
        " e.g., #{store.name}.in_context(context).to { ... }"
      raise ArgumentError, message
    end
    @expected_value = context.instance_eval(&block)
  else
    @expected_value = expected_value
  end
  self
end