fizzbuzz.py

class FizzBuzz:
    def __init__(self, number):
        if FizzBuzz.is_valid_number(number):
            self.number = number

    @property
    def result(self):
        if FizzBuzz.is_divide_by(self.number, (3 * 5)):
            return "FizzBuzz"
        elif FizzBuzz.is_divide_by(self.number, 3):
            return "Fizz"
        elif FizzBuzz.is_divide_by(self.number, 5):
            return "Buzz"
        return self.number

    @staticmethod
    def is_valid_number(number):
        if number <= 0 or number >= 101:
            raise ValueError
        return True

    @staticmethod
    def is_divide_by(number, divider):
        if number % divider == 0:
            return True
        return False

test_fizzbuzz.py

import unittest
from fizzbuzz import FizzBuzz

class TestFizzBuzz(unittest.TestCase):
    def test_0_should_raise_value_error(self):
        with self.assertRaises(ValueError):
            FizzBuzz(0)

    def test_101_should_raise_value_error(self):
        with self.assertRaises(ValueError):
            FizzBuzz(101)

    def test_1_should_return_1(self):
        self.assertEqual(FizzBuzz(1).result, 1)

    def test_2_shuld_return_2(self):
        self.assertEqual(FizzBuzz(2).result, 2)

    def test_3_should_return_fizz(self):
        self.assertEqual(FizzBuzz(3).result, "Fizz")

    def test_6_shuold_return_fizz(self):
        self.assertEqual(FizzBuzz(6).result, "Fizz")

    def test_5_should_return_buzz(self):
        self.assertEqual(FizzBuzz(5).result, "Buzz")

    def test_10_should_return_buzz(self):
        self.assertEqual(FizzBuzz(10).result, "Buzz")

    def tset_15_should_return_fizzbuzz(self):
        self.assertEqual(FizzBuzz(15).result, "FizzBuzz")

    def test_30_should_return_fizzbuzz(self):
        self.assertEqual(FizzBuzz(30).result, "FizzBuzz")