誕生日の前後一週間かどうかを判定したい！

birthday_test.rb

# 準備
#   `gem i activesupport`
#   `gem i rspec`
# 実行
#   `rspec birthday_test.rb`

# 実装
require 'active_support'
require 'active_support/core_ext'
# require 'byebug'

class BirthDay
  def self.around_a_week?(birthday)
    # 元の実装
    # today = Date.today
    # current_year_birthday = "#{today.year}-#{birthday.strftime("%m-%d")}".to_date
    # birthday_prev_week = current_year_birthday - 7
    # birthday_next_week = current_year_birthday + 7

    # today.between?(birthday_prev_week, birthday_next_week) || \
    # today.prev_year.between?(birthday_prev_week, birthday_next_week) || \
    # today.next_year.between?(birthday_prev_week, birthday_next_week)

    # tatsuosakurai案
    # today = Date.today.to_time
    # age = (today.strftime('%Y%m%d').to_i - birthday.strftime('%Y%m%d').to_i) / 10000
    # age += 1 if (birthday + age.year + 7.days) < today
    # from_date = birthday.ago(1.week) + age.year
    # to_date = birthday.since(1.week) + age.year
    # today.between?(from_date, to_date)

    # nay案
    # today = Date.today
    # [ Date.new(today.year-1, birthday.month, birthday.day),
    #   Date.new(today.year, birthday.month, birthday.day),
    #   Date.new(today.year+1, birthday.month, birthday.day)
    # ].map { |d| (d.jd - today.jd).abs }.any? { |v| v <= 7 }

    # suginoy with tatsuosakurai案
    # today = Date.today
    # [ Date.new(today.year - 1, birthday.month, birthday.day),
    #   Date.new(today.year,     birthday.month, birthday.day),
    #   Date.new(today.year + 1, birthday.month, birthday.day)
    # ].select { |d| ((today - 1.week)..(today + 1.week)).cover?(d) }.present?

    # sinsoku案
    # now = Time.current
    # (now.year + 1).downto(birthday.year).any? do |year|
    #   diff = now - birthday.change(year: year)
    #   diff.negative? ? -1.week <= diff : diff < 8.days
    # end

    # sinsoku案2
    # now = Time.current
    # (now.year + 1).downto(birthday.year).any? do |year|
    #   current_birthday = birthday.change(year: year)
    #   from = current_birthday.ago(1.week).beginning_of_day
    #   to = current_birthday.since(1.week).end_of_day

    #   (from..to).cover?(now)
    # end  

    # hmsk案
    # diff = (Time.now.yday - Time.new(Time.now.year, birthday.month, birthday.day).yday).abs
    # diff <= 7 || diff >= Time.new(Time.now.year, 12, 31).yday - 7

    # hanachin_案 https://twitter.com/hanachin_/status/1128844645025247232
    # today = Date.today
    # (-7..7).any? do |n|
    #   date = birthday + n.days
    #   date.month == today.month && date.day == today.day
    # end

    # nay案2
    # dates = (Date.today - 7)..(Date.today + 7)
    # dates.any? { |d| d.month == birthday.month && d.day == birthday.day }  
  end
end

# spec_helper
require 'rspec'
require 'active_support/testing/time_helpers'

RSpec.configure do |config|
  config.include ActiveSupport::Testing::TimeHelpers
end

# spec
RSpec.describe BirthDay do
  describe 'around_a_week?' do
    subject(:around_a_week?) { travel_to(today.to_time) { BirthDay.around_a_week?(birthday) } }

    context '年をまたがない場合' do
      let!(:birthday){ '1985-05-26 0:00'.to_time }

      context '7日前' do
        let!(:today) { '2019-5-19 00:00' }
        it { expect(around_a_week?).to eq true }
      end

      context '8日前' do
        let!(:today) { '2019-5-18 23:59' }
        it { expect(around_a_week?).to eq false }
      end

      context '7日後' do
        let!(:today) { '2019-6-2 23:59' }
        it { expect(around_a_week?).to eq true }
      end

      context '8日後' do
        let!(:today) { '2019-6-3 00:00' }
        it { expect(around_a_week?).to eq false }
      end
    end

    context '年をまたぐ場合' do
      context '年末の場合' do
        let(:birthday){ '1985-12-27 0:00'.to_time }

        context '7日前' do
          let!(:today) { '2019-12-20 00:00' }
          it { expect(around_a_week?).to eq true }
        end

        context '8日前' do
          let!(:today) { '2019-12-19 23:59' }
          it { expect(around_a_week?).to eq false }
        end

        context '7日後' do
          let!(:today) { '2020-1-3 23:59' }
          it { expect(around_a_week?).to eq true }
        end

        context '8日後' do
          let!(:today) { '2020-1-4 00:00' }
          it { expect(around_a_week?).to eq false }
        end
      end

      context '年始の場合' do
        let(:birthday){ '1985-01-03 0:00'.to_time }

        context '7日前' do
          let!(:today) { '2019-12-27 00:00' }
          it { expect(around_a_week?).to eq true }
        end

        context '8日前' do
          let!(:today) { '2019-12-26 23:59' }
          it { expect(around_a_week?).to eq false }
        end

        context '7日後' do
          let!(:today) { '2020-1-10 23:59' }
          it { expect(around_a_week?).to eq true }
        end

        context '8日後' do
          let!(:today) { '2020-1-11 00:00' }
          it { expect(around_a_week?).to eq false }
        end
      end
    end
  end
end

もっといい実装にできないかなあ

思っていたより難しかった...

now = Time.current
(now.year + 1).downto(birthday.year).any? do |year|
  diff = now - birthday.change(year: year)
  diff.negative? ? -1.week <= diff : diff < 8.days
end

こっちの方が読みやすいですね。

now = Time.current
(now.year + 1).downto(birthday.year).any? do |year|
  current_birthday = birthday.change(year: year)
  from = current_birthday.ago(1.week).beginning_of_day
  to = current_birthday.since(1.week).end_of_day

  (from..to).cover?(now)
end

あざまっす！ここまで反映させました（テストが通ることも念の為確認済み:)）

diff = (Time.now.yday - Time.new(Time.now.year, birthday.month, birthday.day).yday).abs
diff <= 7 || diff >= Time.new(Time.now.year, 12, 31).yday - 7

AS無しで。現状のテストケースは通るものの、うるう年に絡むと通らないケースがいくつかありますが時間切れ〜

あざまっす！
うるう年、そういえば〜〜〜＞＜