rspecを使ったfeature specでjavascriptの時間を指定時間に固定するhelper

travel_to_javascript.rb

# === sample ===
# require 'rails_helper'
# require 'helpers/travel_to_javascript'
# RSpec.feature 'sample', type: :feature do
#   it 'sample expect' do
#     travel_to_javascript(page, "2010/11/11 12:00".in_time_zone) do
#       page.execute_script("console.error('now1:', new Date())")
#       page.execute_script("console.error('now2:', Date.now())")
#       pp page.driver.browser.manage.logs.get(:browser).map(&:message)
#       # => ["console-api 0:32 \"now1:\" Thu Nov 11 2010 12:00:00 GMT+0900 (日本標準時)",
#       #     "console-api 0:32 \"now2:\" 1289444400000"]
#     end
#     page.execute_script("console.error('now1:', new Date())")
#     page.execute_script("console.error('now2:', Date.now())")
#     pp page.driver.browser.manage.logs.get(:browser).map(&:message)
#     # => ["console-api 0:32 \"now1:\" Sat Nov 23 2019 18:45:37 GMT+0900 (日本標準時)",
#     #     "console-api 0:32 \"now2:\" 1574502337831"]
#   end
# end

module TravelToJavascript
  def travel_to_javascript(page, datetime)
    page.execute_script time_stop_javascript(datetime)
    yield
    page.execute_script time_undo_javsctipt
  end

  private

  def time_stop_javascript(rb_datetime)
    <<~JS
      originDate = Date;
      Date = #{time_stop_js_function_for_date(rb_datetime)};
      Date.now = #{time_stop_js_function_for_date_now(rb_datetime)};
    JS
  end

  def time_undo_javsctipt
    'Date = originDate;'
  end

  def time_stop_js_function_for_date(rb_datetime)
    <<~JS
      function (datetime) {
        if (datetime) {
          return new originDate(datetime);
        } else {
          return new originDate("#{rb_datetime.iso8601}");
        }
      }
    JS
  end

  def time_stop_js_function_for_date_now(rb_datetime)
    <<~JS
      function (datetime) {
        if (datetime) {
          return new originDate(datetime).getTime();
        } else {
          return new originDate("#{rb_datetime.iso8601}").getTime();
        }
      }
    JS
  end
end

RSpec.configure do |config|
  config.include(TravelToJavascript, :type => :feature)
end