class RuboCop::Cop::Minitest::AssertOperator

def build_new_arguments(node)
  lhs, op, rhs = *node.first_argument
  new_arguments = +"#{lhs.source}, :#{op}, #{rhs.source}"
  if node.arguments.count == 2
    new_arguments << ", #{node.last_argument.source}"
  else
    new_arguments
  end
end

def on_send(node)
  first_argument = node.first_argument
  return unless first_argument.respond_to?(:binary_operation?) && first_argument.binary_operation?
  operator = first_argument.to_a[1]
  return if ALLOWED_OPERATORS.include?(operator)
  new_arguments = build_new_arguments(node)
  add_offense(node, message: format(MSG, new_arguments: new_arguments)) do |corrector|
    corrector.replace(node.loc.selector, 'assert_operator')
    corrector.replace(range_of_arguments(node), new_arguments)
  end
end

def range_of_arguments(node)
  node.first_argument.source_range.begin.join(node.last_argument.source_range.end)
end