module RuboCop::Cop::NegativeConditional

def check_negative_conditional(node)
  condition = node.condition
  return if empty_condition?(condition)
  condition = condition.children.last while condition.begin_type?
  return unless single_negative?(condition)
  return if node.if_type? && node.else?
  add_offense(node, :expression)
end

def negated_condition(node)
  condition = node.condition
  condition = condition.children.first while condition.begin_type?
  condition
end

def negative_conditional_corrector(node)
  condition = negated_condition(node)
  lambda do |corrector|
    corrector.replace(node.loc.keyword, node.inverse_keyword)
    corrector.replace(condition.source_range,
                      condition.children.first.source)
  end
end