beer.py

def number(bottles):
    return str(bottles) if 0 < bottles else "No"


def bottlesOfBeer(bottles):
    s = "" if bottles == 1 else "s"
    return f"{number(bottles)} bottle{s} of beer"


def passOne(bottles):
    if bottles == 0:
        return "There are no more to pass around"
    return "Take one down, pass it around"


def verse():
    return """{bottles} on the wall, {bottles}. {passOne}, {next} on the wall.\n"""


def singVerse(bottles):
    return verse().format(bottles=bottlesOfBeer(bottles),
                          passOne=passOne(bottles),
                          next=bottlesOfBeer(max(0, bottles - 1)))


def sing(bottles):
    return "".join(map(singVerse, range(bottles, -1, -1)))


# Testing
def red(message):
    print("\033[91m {}\033[00m".format(message))


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


def test(name, expected, actual):
    if actual == expected:
        green(name)
    else:
        red("FAIL: " + name)
        print("\nExpected:\n")
        print(expected)
        print("\nActual:\n")
        print(actual)
        print("\n\n")


verse2 = """2 bottles of beer on the wall, 2 bottles of beer. Take one down, pass it around, 1 bottle of beer on the wall.\n"""
verse1 = """1 bottle of beer on the wall, 1 bottle of beer. Take one down, pass it around, No bottles of beer on the wall.\n"""
verse0 = """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.\n"""

test("Given 0, sings the last round.", verse0, sing(0))
test("Given 1, sings verse one and the last round.", verse1 + verse0, sing(1))
test("Given 2, sings three verses.", verse2 + verse1 + verse0, sing(2))

print(sing(99))