diy-pager-total-pages.rb

require "minitest/autorun"
require "minitest/spec"

class Pager
  def initialize(total_rows:, rows_per_page:)
    @total_rows = total_rows
    @rows_per_page = rows_per_page
  end

  def total_pages
    (@total_rows/@rows_per_page.to_f).ceil
  end
end

describe Pager do
  describe "#total_pages" do
    it "rounds up to the next whole number" do
      pager = Pager.new(total_rows: 33, rows_per_page: 10)
      assert_equal pager.total_pages, 4
    end

    it "returns 1 when there are less than rows_per_page" do
      pager = Pager.new(total_rows: 3, rows_per_page: 10)
      assert_equal pager.total_pages, 1
    end

    it "returns 0 when there are 0 rows" do
      pager = Pager.new(total_rows: 0, rows_per_page: 10)
      assert_equal pager.total_pages, 0
    end
  end
end