file.rb

class Array

  def includes_a?(other_array)
    self | other_array == self
  end

  def includes_b?(other_array)
    (other_array - self).empty?
  end

  def includes_c?(other_array)
    self & other_array == other_array
  end

  def includes_d?(other_array)
    (self + other_array).uniq == self
  end

  def includes_e?(other_array)
    self | other_array == self & other_array
  end

  def includes_f?(other_array)
    other_array.all? {|e| include?(e) }
  end
end

p [1,2,3].includes_b?([2,3]) #=> true
p [1,2,3].includes_b?([3,4]) #=> false

require 'benchmark'

N = 100_000

Benchmark.bm do |b|
  b.report('a') do
    N.times do
      [1,2,3].includes_a?([2,3]) #=> true
      [1,2,3].includes_a?([3,4]) #=> false
    end
  end
  b.report('b') do
    N.times do
      [1,2,3].includes_b?([2,3]) #=> true
      [1,2,3].includes_b?([3,4]) #=> false
    end
  end
  b.report('c') do
    N.times do
      [1,2,3].includes_c?([2,3]) #=> true
      [1,2,3].includes_c?([3,4]) #=> false
    end
  end
  b.report('d') do
    N.times do
      [1,2,3].includes_d?([2,3]) #=> true
      [1,2,3].includes_d?([3,4]) #=> false
    end
  end
  b.report('e') do
    N.times do
      [1,2,3].includes_e?([2,3]) #=> true
      [1,2,3].includes_e?([3,4]) #=> false
    end
  end
  b.report('f') do
    N.times do
      [1,2,3].includes_f?([2,3]) #=> true
      [1,2,3].includes_f?([3,4]) #=> false
    end
  end
end