Ruby date

usage_interval.rb

class UsageInterval

  def initialize(date)
    day_of_the_week = date.cwday
    @end = date - day_of_the_week
    @begin = @end - 7
  end

  def self.usageIntervalFromPreviousWeek date = Date.today
    UsageInterval.new date
  end

  def begin
    @begin.to_time.to_i
  end

  def end
    @end.to_time.to_i
  end

end

usage_interval_spec.rb

require 'rspec'
require 'date'
require_relative '../../lib/domain/usage_interval'

describe UsageInterval do

  it 'should return the current week start as interval ending' do
    date = Date.new 2021, 9, 25 # 2021-09-25

    interval_end_date = UsageInterval::usageIntervalFromPreviousWeek(date).end

    expect(interval_end_date).to eq(Date.new(2021, 9, 19).to_time.to_i)  #2021-09-19
  end

  it 'should return the previous week start as interval start' do
    date = Date.new 2021, 9, 25# 2021-09-25

    interval_begin_date = UsageInterval::usageIntervalFromPreviousWeek(date).begin

    expect(interval_begin_date).to eq(Date.new(2021, 9, 12).to_time.to_i) #  2021-09-12
  end

  it 'should return the previous week end even when the date is sunday' do
    date = Date.new 2021, 9, 19# 2021-09-25

    interval_end_date = UsageInterval::usageIntervalFromPreviousWeek(date).end

    expect(interval_end_date).to eq(Date.new(2021, 9, 12).to_time.to_i) #  2021-09-12
  end

end