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Testing Poker Hand Evaluation System in TheAlgorithms/Python

A comprehensive test suite for a poker hand evaluation system, validating poker hand comparison logic and game rules implementation in Python. The tests cover hand ranking, card combinations, and various poker scenarios using pytest framework.

Test Coverage Overview

Extensive test coverage for poker hand evaluation including:

Flush detection and validation
Straight hand identification
Multiple card combination checks (pairs, three-of-a-kind, etc.)
Hand comparison scenarios
Random hand generation testing
Special case handling for five-high straights

Implementation Analysis

The testing approach utilizes pytest’s parametrize feature for data-driven testing, enabling comprehensive validation of poker hand logic. The implementation includes systematic verification of hand rankings, card combinations, and comparison operations with detailed test fixtures and assertions.

Technical Details

Testing tools and configuration:

pytest framework for test execution
Custom PokerHand class implementation
File-based test data for Project Euler validation
Parametrized test cases for multiple scenarios
Random hand generation for edge case testing

Best Practices Demonstrated

The test suite exemplifies strong testing practices including:

Comprehensive edge case coverage
Parameterized test cases for maintainability
Isolation of test scenarios
Clear test case organization
Integration with external test data
Validation of complex game rules

thealgorithms/python

project_euler/problem_054/test_poker_hand.py

            
import os
from itertools import chain
from random import randrange, shuffle

import pytest

from .sol1 import PokerHand

SORTED_HANDS = (
    "4S 3H 2C 7S 5H",
    "9D 8H 2C 6S 7H",
    "2D 6D 9D TH 7D",
    "TC 8C 2S JH 6C",
    "JH 8S TH AH QH",
    "TS KS 5S 9S AC",
    "KD 6S 9D TH AD",
    "KS 8D 4D 9S 4S",  # pair
    "8C 4S KH JS 4D",  # pair
    "QH 8H KD JH 8S",  # pair
    "KC 4H KS 2H 8D",  # pair
    "KD 4S KC 3H 8S",  # pair
    "AH 8S AS KC JH",  # pair
    "3H 4C 4H 3S 2H",  # 2 pairs
    "5S 5D 2C KH KH",  # 2 pairs
    "3C KH 5D 5S KH",  # 2 pairs
    "AS 3C KH AD KH",  # 2 pairs
    "7C 7S 3S 7H 5S",  # 3 of a kind
    "7C 7S KH 2H 7H",  # 3 of a kind
    "AC KH QH AH AS",  # 3 of a kind
    "2H 4D 3C AS 5S",  # straight (low ace)
    "3C 5C 4C 2C 6H",  # straight
    "6S 8S 7S 5H 9H",  # straight
    "JS QS 9H TS KH",  # straight
    "QC KH TS JS AH",  # straight (high ace)
    "8C 9C 5C 3C TC",  # flush
    "3S 8S 9S 5S KS",  # flush
    "4C 5C 9C 8C KC",  # flush
    "JH 8H AH KH QH",  # flush
    "3D 2H 3H 2C 2D",  # full house
    "2H 2C 3S 3H 3D",  # full house
    "KH KC 3S 3H 3D",  # full house
    "JC 6H JS JD JH",  # 4 of a kind
    "JC 7H JS JD JH",  # 4 of a kind
    "JC KH JS JD JH",  # 4 of a kind
    "2S AS 4S 5S 3S",  # straight flush (low ace)
    "2D 6D 3D 4D 5D",  # straight flush
    "5C 6C 3C 7C 4C",  # straight flush
    "JH 9H TH KH QH",  # straight flush
    "JH AH TH KH QH",  # royal flush (high ace straight flush)
)

TEST_COMPARE = (
    ("2H 3H 4H 5H 6H", "KS AS TS QS JS", "Loss"),
    ("2H 3H 4H 5H 6H", "AS AD AC AH JD", "Win"),
    ("AS AH 2H AD AC", "JS JD JC JH 3D", "Win"),
    ("2S AH 2H AS AC", "JS JD JC JH AD", "Loss"),
    ("2S AH 2H AS AC", "2H 3H 5H 6H 7H", "Win"),
    ("AS 3S 4S 8S 2S", "2H 3H 5H 6H 7H", "Win"),
    ("2H 3H 5H 6H 7H", "2S 3H 4H 5S 6C", "Win"),
    ("2S 3H 4H 5S 6C", "3D 4C 5H 6H 2S", "Tie"),
    ("2S 3H 4H 5S 6C", "AH AC 5H 6H AS", "Win"),
    ("2S 2H 4H 5S 4C", "AH AC 5H 6H AS", "Loss"),
    ("2S 2H 4H 5S 4C", "AH AC 5H 6H 7S", "Win"),
    ("6S AD 7H 4S AS", "AH AC 5H 6H 7S", "Loss"),
    ("2S AH 4H 5S KC", "AH AC 5H 6H 7S", "Loss"),
    ("2S 3H 6H 7S 9C", "7H 3C TH 6H 9S", "Loss"),
    ("4S 5H 6H TS AC", "3S 5H 6H TS AC", "Win"),
    ("2S AH 4H 5S 6C", "AD 4C 5H 6H 2C", "Tie"),
    ("AS AH 3H AD AC", "AS AH 2H AD AC", "Win"),
    ("AH AC 5H 5C QS", "AH AC 5H 5C KS", "Loss"),
    ("AH AC 5H 5C QS", "KH KC 5H 5C QS", "Win"),
    ("7C 7S KH 2H 7H", "3C 3S AH 2H 3H", "Win"),
    ("3C 3S AH 2H 3H", "7C 7S KH 2H 7H", "Loss"),
    ("6H 5H 4H 3H 2H", "5H 4H 3H 2H AH", "Win"),
    ("5H 4H 3H 2H AH", "5H 4H 3H 2H AH", "Tie"),
    ("5H 4H 3H 2H AH", "6H 5H 4H 3H 2H", "Loss"),
    ("AH AD KS KC AC", "AH KD KH AC KC", "Win"),
    ("2H 4D 3C AS 5S", "2H 4D 3C 6S 5S", "Loss"),
    ("2H 3S 3C 3H 2S", "3S 3C 2S 2H 2D", "Win"),
    ("4D 6D 5D 2D JH", "3S 8S 3H TC KH", "Loss"),
    ("4S 6C 8S 3S 7S", "AD KS 2D 7D 7C", "Loss"),
    ("6S 4C 7H 8C 3H", "5H JC AH 9D 9C", "Loss"),
    ("9D 9H JH TC QH", "3C 2S JS 5C 7H", "Win"),
    ("2H TC 8S AD 9S", "4H TS 7H 2C 5C", "Win"),
    ("9D 3S 2C 7S 7C", "JC TD 3C TC 9H", "Loss"),
)

TEST_FLUSH = (
    ("2H 3H 4H 5H 6H", True),
    ("AS AH 2H AD AC", False),
    ("2H 3H 5H 6H 7H", True),
    ("KS AS TS QS JS", True),
    ("8H 9H QS JS TH", False),
    ("AS 3S 4S 8S 2S", True),
)

TEST_STRAIGHT = (
    ("2H 3H 4H 5H 6H", True),
    ("AS AH 2H AD AC", False),
    ("2H 3H 5H 6H 7H", False),
    ("KS AS TS QS JS", True),
    ("8H 9H QS JS TH", True),
)

TEST_FIVE_HIGH_STRAIGHT = (
    ("2H 4D 3C AS 5S", True, [5, 4, 3, 2, 14]),
    ("2H 5D 3C AS 5S", False, [14, 5, 5, 3, 2]),
    ("JH QD KC AS TS", False, [14, 13, 12, 11, 10]),
    ("9D 3S 2C 7S 7C", False, [9, 7, 7, 3, 2]),
)

TEST_KIND = (
    ("JH AH TH KH QH", 0),
    ("JH 9H TH KH QH", 0),
    ("JC KH JS JD JH", 7),
    ("KH KC 3S 3H 3D", 6),
    ("8C 9C 5C 3C TC", 0),
    ("JS QS 9H TS KH", 0),
    ("7C 7S KH 2H 7H", 3),
    ("3C KH 5D 5S KH", 2),
    ("QH 8H KD JH 8S", 1),
    ("2D 6D 9D TH 7D", 0),
)

TEST_TYPES = (
    ("JH AH TH KH QH", 23),
    ("JH 9H TH KH QH", 22),
    ("JC KH JS JD JH", 21),
    ("KH KC 3S 3H 3D", 20),
    ("8C 9C 5C 3C TC", 19),
    ("JS QS 9H TS KH", 18),
    ("7C 7S KH 2H 7H", 17),
    ("3C KH 5D 5S KH", 16),
    ("QH 8H KD JH 8S", 15),
    ("2D 6D 9D TH 7D", 14),
)


def generate_random_hand():
    play, oppo = randrange(len(SORTED_HANDS)), randrange(len(SORTED_HANDS))
    expected = ["Loss", "Tie", "Win"][(play >= oppo) + (play > oppo)]
    hand, other = SORTED_HANDS[play], SORTED_HANDS[oppo]
    return hand, other, expected


def generate_random_hands(number_of_hands: int = 100):
    return (generate_random_hand() for _ in range(number_of_hands))


@pytest.mark.parametrize(("hand", "expected"), TEST_FLUSH)
def test_hand_is_flush(hand, expected):
    assert PokerHand(hand)._is_flush() == expected


@pytest.mark.parametrize(("hand", "expected"), TEST_STRAIGHT)
def test_hand_is_straight(hand, expected):
    assert PokerHand(hand)._is_straight() == expected


@pytest.mark.parametrize(("hand", "expected", "card_values"), TEST_FIVE_HIGH_STRAIGHT)
def test_hand_is_five_high_straight(hand, expected, card_values):
    player = PokerHand(hand)
    assert player._is_five_high_straight() == expected
    assert player._card_values == card_values


@pytest.mark.parametrize(("hand", "expected"), TEST_KIND)
def test_hand_is_same_kind(hand, expected):
    assert PokerHand(hand)._is_same_kind() == expected


@pytest.mark.parametrize(("hand", "expected"), TEST_TYPES)
def test_hand_values(hand, expected):
    assert PokerHand(hand)._hand_type == expected


@pytest.mark.parametrize(("hand", "other", "expected"), TEST_COMPARE)
def test_compare_simple(hand, other, expected):
    assert PokerHand(hand).compare_with(PokerHand(other)) == expected


@pytest.mark.parametrize(("hand", "other", "expected"), generate_random_hands())
def test_compare_random(hand, other, expected):
    assert PokerHand(hand).compare_with(PokerHand(other)) == expected


def test_hand_sorted():
    poker_hands = [PokerHand(hand) for hand in SORTED_HANDS]
    list_copy = poker_hands.copy()
    shuffle(list_copy)
    user_sorted = chain(sorted(list_copy))
    for index, hand in enumerate(user_sorted):
        assert hand == poker_hands[index]


def test_custom_sort_five_high_straight():
    # Test that five high straights are compared correctly.
    pokerhands = [PokerHand("2D AC 3H 4H 5S"), PokerHand("2S 3H 4H 5S 6C")]
    pokerhands.sort(reverse=True)
    assert pokerhands[0].__str__() == "2S 3H 4H 5S 6C"


def test_multiple_calls_five_high_straight():
    # Multiple calls to five_high_straight function should still return True
    # and shouldn't mutate the list in every call other than the first.
    pokerhand = PokerHand("2C 4S AS 3D 5C")
    expected = True
    expected_card_values = [5, 4, 3, 2, 14]
    for _ in range(10):
        assert pokerhand._is_five_high_straight() == expected
        assert pokerhand._card_values == expected_card_values


def test_euler_project():
    # Problem number 54 from Project Euler
    # Testing from poker_hands.txt file
    answer = 0
    script_dir = os.path.abspath(os.path.dirname(__file__))
    poker_hands = os.path.join(script_dir, "poker_hands.txt")
    with open(poker_hands) as file_hand:
        for line in file_hand:
            player_hand = line[:14].strip()
            opponent_hand = line[15:].strip()
            player, opponent = PokerHand(player_hand), PokerHand(opponent_hand)
            output = player.compare_with(opponent)
            if output == "Win":
                answer += 1
    assert answer == 376