prime.rb

# encoding: utf-8
class Prime
  def initialize(n)
    @n = n
  end

  def calculate
    result = [1]
    (2..@n).each do |n|
      result << n if (2..n-1).all? do |factor|
         n % factor != 0
      end
    end
    result
  end
end


if __FILE__ == $0
  require 'test/unit'
  require 'minitest/spec'
  describe Prime do
    it "accept a number" do
      proc {
        Prime.new
      }.must_raise ArgumentError
    end
    it "calculate returns a list" do
      Prime.new(5).calculate.must_be_instance_of Array
    end
    it "returns a list includes 1" do
      Prime.new(5).calculate.must_include 1
    end
    it "returns a list includes 1, 2, 3, 5, 7 when input argument is 7" do
      Prime.new(7).calculate.must_equal [1,2,3,5,7]
    end

  end
end