beer_oop.py

class Verse:

    def create(bottles):
        return {
            0: UltimateVerse(),
            1: PenultimateVerse()
        }.get(bottles, Verse(bottles))

    def __init__(self, bottles):
        self.bottles = bottles

    def sing(self):
        return (
            f"{self.bottlesOfBeer()} on the wall, {self.bottlesOfBeer()}. " +
            f"{self._passOne()}, {self._next()} on the wall.")

    def bottlesOfBeer(self):
        return f"{self.bottles} bottles of beer"

    def _passOne(self):
        return "Take one down, pass it around"

    def _next(self):
        return Verse.create(self.bottles - 1).bottlesOfBeer()


class PenultimateVerse(Verse):

    def __init__(self):
        self.bottles = 1

    def bottlesOfBeer(self):
        return "1 bottle of beer"


class UltimateVerse(Verse):

    def __init__(self):
        self.bottles = 0

    def bottlesOfBeer(self):
        return "No bottles of beer"

    def _passOne(self):
        return "There are no more to pass around"

    def _next(self):
        return self.bottlesOfBeer()


class Song:

    def sing(self):
        return "\n".join(
            map(lambda b: self.__verse(b), range(self.bottles, -1, -1)))

    def __init__(self, bottles):
        self.bottles = bottles

    def __verse(self, bottles):
        return Verse.create(bottles).sing()


# Testing
class Test:

    def __init__(self, expected, actual):
      self.expected = expected
      self.actual = actual

    def run(self):
        if self.actual == self.expected:
            self.__green(self.__class__.__name__)
        else:
            self.__red("FAIL: " + self.__class__.__name__)
            print(f"\nExpected:\n{self.expected}\n\nActual:\n{self.actual}\n\n")
            raise Exception("FAIL")

    def __red(self, message):
        print("\033[91m {}\033[00m".format(message))

    def __green(self, message):
        print("\033[92m {}\033[00m".format(message))



__verses = {
    2:
    "2 bottles of beer on the wall, 2 bottles of beer. Take one down, pass it around, 1 bottle of beer on the wall.",
    1:
    "1 bottle of beer on the wall, 1 bottle of beer. Take one down, pass it around, No bottles of beer on the wall.",
    0:
    "No bottles of beer on the wall, No bottles of beer. There are no more to pass around, No bottles of beer on the wall."
}

def lyrics(*verseNumbers):
    return "\n".join(map(lambda i: __verses[i], verseNumbers))

class Given0_SingsTheLastRound(Test):
  def __init__(self):
    self.expected = lyrics(0)
    self.actual = Song(0).sing()

class Given1_SingsVerseOneAndTheLastRound(Test):
  def __init__(self):
    self.expected = lyrics(1, 0)
    self.actual = Song(1).sing()

class Given2_SingsThreeVerses(Test):
  def __init__(self):
    self.expected = lyrics(2, 1, 0)
    self.actual = Song(2).sing()


Given0_SingsTheLastRound().run()
Given1_SingsVerseOneAndTheLastRound().run()
Given2_SingsThreeVerses().run()

print(Song(99).sing())