Rubocop Lint: Useless assignment to variable - ruby

Question

This code runs perfectly in the console but the linters keep failing with the error below..
This is the error:
refactored.rb:17:5: W: Lint/UselessAssignment: Useless assignment to variable - user_name. Did you mean user_age?
user_name = gets.chomp
refactored.rb:14:5: W: Lint/UselessAssignment: Useless assignment to variable - user_age. Did you mean user_name?
user_age = Integer(gets.chomp)
^^^^^^^^
This is the code:
require './school-library/student'
require './school-library/rental'
require './school-library/persons'
require './school-library/teacher'
require './school-library/book'
class Methods
def initialize
#person_array = []
end
def user_input
print 'Age: '
user_age = Integer(gets.chomp)
print 'Name: '
user_name = gets.chomp
end
def create_person
puts 'Do you want to create a student (1) or a teacher (2)? [Input the number]: '
person_option = Integer(gets.chomp)
case person_option
when 1
(user_age, user_name) = user_input
print 'Has parent permission? [Y/N]: '
user_permission = gets.chomp.to_s.upcase
case user_permission
when 'Y'
user_permission = true
when 'N'
user_permission = false
end
student = Student.new(user_age, user_name, parent_permission: user_permission)
#person_array.push({
output: "[Student] Name: #{student.name}, ID: #{student.id}, Age: #{student.age}",
object: student
})
puts 'Person created successfully!'
puts "\n"
when 2
(user_age, user_name) = user_input
print 'Specialization: '
user_specialization = gets.chomp
teacher = Teachers.new(user_age, user_name, user_specialization)
#person_array.push({
output: "[Teacher] Name: #{teacher.name}, ID: #{teacher.id}, Age: #{teacher.age}",
object: teacher
})
puts 'Person created successfully!'
puts "\n"
else
puts 'Person not created.'
end
end
def people_list
#person_array.each do |person|
puts person[:output]
end
end
def person_rent
#person_array.each_with_index do |person, index|
puts "#{index}) #{person[:output]}"
end
end
end
class BooksList
def initialize
#books = []
end
def create_book
print 'Title: '
book_title = gets.chomp
print 'Author: '
book_author = gets.chomp
puts 'Book created successfully!'
book = Book.new(book_title, book_author)
#books.push({
output: "Title: #{book.title}, Author: #{book.author}",
object: book
})
end
def book_list
#books.each do |book|
puts book[:output]
end
end
def rent_book
#books.each_with_index do |book, index|
puts "#{index}) #{book[:output]}"
end
end
end

Answer 1

RuboCop is trying to tell you that a useless variable exists in your code, but before fix that we need to talk about a bug happening right here:
(user_age, user_name) = user_input
In Ruby, a method returns the last line of code. Looking at the method user_input we can see that it returns only the user_name variable. The problem is that the (user_age, user_name) expects two values. The first is being assigned, but the second is given nil.
To fix that, update the method user_input to:
def user_input
print 'Age: '
user_age = Integer(gets.chomp)
print 'Name: '
user_name = gets.chomp
[user_age, user_name]
end
This will fix both the RuboCop offense and the bug.