d20.py

import unittest
import random
from typing import List


class D20:
    minimum_value: int = 1
    maximum_value: int = 20
    number_range: List[int] = range(minimum_value, maximum_value + 1)

    def __init__(self) -> None:
        self.value = None

    def roll(self):
        self.value = random.choice(self.number_range)


class TestD20(unittest.TestCase):
    def test_initialization(self):
        testobj = D20()
        expected_minimum_value = 1
        expected_maximum_value = 20
        self.assertEqual(expected_minimum_value, testobj.minimum_value)
        self.assertEqual(expected_maximum_value, testobj.maximum_value)
        self.assertIsNone(testobj.value)

    def test_value_changes_from_default_value(self):
        testobj = D20()
        testobj.roll()
        actual_value = testobj.value
        self.assertIsNotNone(actual_value)

    def test_roll_returns_number_within_bounds(self):
        testobj = D20()
        testobj.roll()
        actual_roll = testobj.value
        self.assertIn(actual_roll, testobj.number_range)

    def test_roll_is_not_static(self):
        testobj = D20()
        roll_values = []
        for i in range(20):
            testobj.roll()
            roll_values.append(testobj.value)

        unique_roll_values = list(set(roll_values))
        self.assertGreater(len(unique_roll_values), 1)

    def test_roll_hits_every_number(self):
        testobj = D20()
        roll_values = []
        for i in range(100):
            testobj.roll()
            roll_values.append(testobj.value)

        unique_roll_values = list(set(roll_values))
        for i in range(1, 21):
            self.assertIn(i, unique_roll_values)


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