clock.py

import unittest
import os
import time

class Clock:

  WORK_DAYS = 22
  AVERAGE_SALARY = 4000.0
  WORK_HOURS = 8

  def __init__(self, minutes = 0):
    self.minutes = minutes
    self.cost = 0

  def running_cost(self, person):
   return round(Clock.minute_rate(person) * self.minutes, 2)

  def tick(self):
   self.minutes+=1

  @classmethod
  def hourly_rate(cls, person = 1):
    return (cls.AVERAGE_SALARY/cls.WORK_DAYS/cls.WORK_HOURS) * person

  @classmethod
  def minute_rate(cls, person = 1):
    return (cls.hourly_rate()/60) * person

  @classmethod
  def start(cls, person):
    clock = Clock()
    while True:
      os.system('clear')
      print "We've been here for %d minutes and it has cost us $%.2f" % (clock.minutes, clock.running_cost(person))
      clock.tick()
      time.sleep(60)


class TestClock(unittest.TestCase):

  def setUp(self):
    self.minutes = 5
    self.clock = Clock(self.minutes)

  def test_work_days_has_correct_value(self):
    self.assertEqual(Clock.WORK_DAYS, 22, "assumes that there are 22 working days in a month")

  def test_average_salary_has_correct_value(self):
    self.assertEqual(Clock.AVERAGE_SALARY, 4000.0, "assumes that the average salary is 4000 a month")

  def test_work_hours_has_correct_value(self):
    self.assertEqual(Clock.WORK_HOURS, 8, "assumes that people work for 8 hours a day")

  def test_hourly_rate_calculation(self):
    self.assertEqual(Clock.hourly_rate(), self.hourly_rate(), "computes how much a person earns per hour")

  def test_single_person_minute_rate(self):
    self.assertEqual(Clock.minute_rate(1), self.minute_rate(),"computes how much this meeting costs given 1 person")

  def test_two_persons_minute_rate(self):
    self.assertEqual(Clock.minute_rate(2), self.minute_rate()*2,"computes how much this meeting costs given 2 persons")

  def test_running_cost_calculation_for_single_person(self):
    self.assertEqual(self.clock.running_cost(1), round(self.minute_rate() * 1 * self.minutes, 2), 'knows the running cost given the # of minutes given 1 persons')

  def test_running_cost_calculation_for_two_persons(self):
    self.assertEqual(self.clock.running_cost(2), round(self.minute_rate() * 2 * self.minutes, 2), 'knows the running cost given the # of minutes given 2 persons')

  def hourly_rate(self):
    return 4000.0/22/8

  def minute_rate(self):
    return self.hourly_rate()/60

if __name__ == '__main__':
    unittest.main()