class Rubocop::Cop::Style::FormatString

argument is an array literal.
if the first argument is a string literal and if the second
manner for all cases, so only two scenarios are considered -
The detection of String#% cannot be implemented in a reliable
Valid options include Kernel#format, Kernel#sprintf and String#%.
This cop enforces the use of a single string formatting utility.

def format?(node) 

def format?(node)
  command?(:format, node)
end

def message(node) 

def message(node)
  _receiver_node, method_name, *_arg_nodes = *node
  preferred =
    if style == :percent
      'String#%'
    else
      style
    end
  method_name = 'String#%' if method_name == :%
  "Favor #{preferred} over #{method_name}."
end

def offending_node?(node) 

def offending_node?(node)
  case style
  when :format
    sprintf?(node) || percent?(node)
  when :sprintf
    format?(node) || percent?(node)
  when :percent
    format?(node) || sprintf?(node)
  end
end

def on_send(node) 

def on_send(node)
  add_offense(node, :selector) if offending_node?(node)
end

def percent?(node) 

def percent?(node)
  receiver_node, method_name, *arg_nodes = *node
  method_name == :% &&
    ([:str, :dstr].include?(receiver_node.type) ||
     arg_nodes[0].type == :array)
end

def sprintf?(node) 

def sprintf?(node)
  command?(:sprintf, node)
end