Hi, dev.to!
Here is my first post there. I hope there are people who like mind games. So I would like to introduce you to some interesting puzzles.

1. Choose the correct result of the code (ruby 3.0):

{ language: 'ruby’, 'position' => 'engineer' }.transform_keys({ language: 'rust’ }, &:to_sym)

• {"rust"=>"ruby", :position=>"engineer"}
• { :rust => 'ruby', :position => 'engineer' }
• { "rust" => :ruby, 'position' => :engineer }
• { :rust => :ruby, :position => :engineer }

2. Choose the correct result of the code (ruby 3.0):

{ e: :n, g: :i, n: :e, e: :r }.except(:e)

• NoMethodError (undefined method 'except')
• {:g=>:i, :n=>:e}
• {:g=>:i, :n=>:e, :e => :r}
• {:e => :n, :g=>:i, :n=>:e}

3. Choose the wrong way to call a lambda

• ->(){}::call
• ->(){}[]
• ->(){}()
• ->(){}::===

4. Choose the correct result of the code

!?q::!. |001

• true
• false
• raise an error
• 1

5. Choose the correct way to create an array [0,1,2,3,4,5]

• Array[0..5]
• (0..4).take(5)
• [*0..5]
• String(012345).split('').map(&:to_i)

6. There is a code

class Animal
  @@count = 0

  def self.inc
    @@count += 1
  end

  def self.count
    @@count
  end  
end

class Cat < Animal
  @@count = 100

  def self.count
    @@count
  end
end

Animal.inc
Cat.inc

Choose the correct result of the code

[Animal.count, Cat.count]

• [1, 101]
• [101, 101]
• [1, 102]
• [102, 102]

7. There is a code

class Item
  def self.count
    $COUNT
  end

  def self.increment
    $COUNT += 1
  end
end

BEGIN { $COUNT = 0 }
Item.increment

Choose the correct result of the code

Item.count

• 0
• 1
• 101
• undefined method '+' for nil:NilClass