class RuboCop::Cop::Style::UnlessElse

This cop looks for unless expressions with else clauses.

def on_if(node) 

def on_if(node)
  loc = node.loc
  # discard ternary ops and modifier if/unless nodes
  return unless loc.respond_to?(:keyword) && loc.respond_to?(:else)
  return unless loc.keyword.is?('unless') && loc.else
  add_offense(node, :expression)
end