exercism-solutions/rust/poker/tests/poker.rs

use poker::*;
use std::collections::HashSet;

#[test]
fn single_hand_always_wins() {
    let input = &["4S 5S 7H 8D JC"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["4S 5S 7H 8D JC"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn highest_card_out_of_all_hands_wins() {
    let input = &["4D 5S 6S 8D 3C", "2S 4C 7S 9H 10H", "3S 4S 5D 6H JH"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["3S 4S 5D 6H JH"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn a_tie_has_multiple_winners() {
    let input = &[
        "4D 5S 6S 8D 3C",
        "2S 4C 7S 9H 10H",
        "3S 4S 5D 6H JH",
        "3H 4H 5C 6C JD",
    ];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["3S 4S 5D 6H JH", "3H 4H 5C 6C JD"]
        .into_iter()
        .collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn multiple_hands_with_the_same_high_cards_tie_compares_next_highest_ranked_down_to_last_card() {
    let input = &["3S 5H 6S 8D 7H", "2S 5D 6D 8C 7S"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["3S 5H 6S 8D 7H"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn winning_high_card_hand_also_has_the_lowest_card() {
    let input = &["2S 5H 6S 8D 7H", "3S 4D 6D 8C 7S"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["2S 5H 6S 8D 7H"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn one_pair_beats_high_card() {
    let input = &["4S 5H 6C 8D KH", "2S 4H 6S 4D JH"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["2S 4H 6S 4D JH"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn highest_pair_wins() {
    let input = &["4S 2H 6S 2D JH", "2S 4H 6C 4D JD"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["2S 4H 6C 4D JD"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn both_hands_have_the_same_pair_high_card_wins() {
    let input = &["4H 4S AH JC 3D", "4C 4D AS 5D 6C"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["4H 4S AH JC 3D"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn two_pairs_beats_one_pair() {
    let input = &["2S 8H 6S 8D JH", "4S 5H 4C 8C 5C"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["4S 5H 4C 8C 5C"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn both_hands_have_two_pairs_highest_ranked_pair_wins() {
    let input = &["2S 8H 2D 8D 3H", "4S 5H 4C 8S 5D"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["2S 8H 2D 8D 3H"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn both_hands_have_two_pairs_with_the_same_highest_ranked_pair_tie_goes_to_low_pair() {
    let input = &["2S QS 2C QD JH", "JD QH JS 8D QC"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["JD QH JS 8D QC"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn both_hands_have_two_identically_ranked_pairs_tie_goes_to_remaining_card_kicker() {
    let input = &["JD QH JS 8D QC", "JS QS JC 2D QD"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["JD QH JS 8D QC"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn both_hands_have_two_pairs_that_add_to_the_same_value_win_goes_to_highest_pair() {
    let input = &["6S 6H 3S 3H AS", "7H 7S 2H 2S AC"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["7H 7S 2H 2S AC"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn two_pairs_first_ranked_by_largest_pair() {
    let input = &["5C 2S 5S 4H 4C", "6S 2S 6H 7C 2C"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["6S 2S 6H 7C 2C"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn three_of_a_kind_beats_two_pair() {
    let input = &["2S 8H 2H 8D JH", "4S 5H 4C 8S 4H"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["4S 5H 4C 8S 4H"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn both_hands_have_three_of_a_kind_tie_goes_to_highest_ranked_triplet() {
    let input = &["2S 2H 2C 8D JH", "4S AH AS 8C AD"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["4S AH AS 8C AD"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn with_multiple_decks_two_players_can_have_same_three_of_a_kind_ties_go_to_highest_remaining_cards(
) {
    let input = &["5S AH AS 7C AD", "4S AH AS 8C AD"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["4S AH AS 8C AD"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn a_straight_beats_three_of_a_kind() {
    let input = &["4S 5H 4C 8D 4H", "3S 4D 2S 6D 5C"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["3S 4D 2S 6D 5C"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn aces_can_end_a_straight_10_j_q_k_a() {
    let input = &["4S 5H 4C 8D 4H", "10D JH QS KD AC"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["10D JH QS KD AC"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn aces_can_start_a_straight_a_2_3_4_5() {
    let input = &["4S 5H 4C 8D 4H", "4D AH 3S 2D 5C"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["4D AH 3S 2D 5C"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn aces_cannot_be_in_the_middle_of_a_straight_q_k_a_2_3() {
    let input = &["2C 3D 7H 5H 2S", "QS KH AC 2D 3S"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["2C 3D 7H 5H 2S"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn both_hands_with_a_straight_tie_goes_to_highest_ranked_card() {
    let input = &["4S 6C 7S 8D 5H", "5S 7H 8S 9D 6H"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["5S 7H 8S 9D 6H"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn even_though_an_ace_is_usually_high_a_5_high_straight_is_the_lowest_scoring_straight() {
    let input = &["2H 3C 4D 5D 6H", "4S AH 3S 2D 5H"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["2H 3C 4D 5D 6H"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn flush_beats_a_straight() {
    let input = &["4C 6H 7D 8D 5H", "2S 4S 5S 6S 7S"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["2S 4S 5S 6S 7S"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn both_hands_have_a_flush_tie_goes_to_high_card_down_to_the_last_one_if_necessary() {
    let input = &["2H 7H 8H 9H 6H", "3S 5S 6S 7S 8S"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["2H 7H 8H 9H 6H"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn full_house_beats_a_flush() {
    let input = &["3H 6H 7H 8H 5H", "4S 5H 4C 5D 4H"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["4S 5H 4C 5D 4H"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn both_hands_have_a_full_house_tie_goes_to_highest_ranked_triplet() {
    let input = &["4H 4S 4D 9S 9D", "5H 5S 5D 8S 8D"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["5H 5S 5D 8S 8D"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn with_multiple_decks_both_hands_have_a_full_house_with_the_same_triplet_tie_goes_to_the_pair() {
    let input = &["5H 5S 5D 9S 9D", "5H 5S 5D 8S 8D"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["5H 5S 5D 9S 9D"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn four_of_a_kind_beats_a_full_house() {
    let input = &["4S 5H 4D 5D 4H", "3S 3H 2S 3D 3C"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["3S 3H 2S 3D 3C"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn both_hands_have_four_of_a_kind_tie_goes_to_high_quad() {
    let input = &["2S 2H 2C 8D 2D", "4S 5H 5S 5D 5C"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["4S 5H 5S 5D 5C"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn with_multiple_decks_both_hands_with_identical_four_of_a_kind_tie_determined_by_kicker() {
    let input = &["3S 3H 2S 3D 3C", "3S 3H 4S 3D 3C"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["3S 3H 4S 3D 3C"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn straight_flush_beats_four_of_a_kind() {
    let input = &["4S 5H 5S 5D 5C", "7S 8S 9S 6S 10S"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["7S 8S 9S 6S 10S"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn aces_can_end_a_straight_flush_10_j_q_k_a() {
    let input = &["KC AH AS AD AC", "10C JC QC KC AC"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["10C JC QC KC AC"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn aces_can_start_a_straight_flush_a_2_3_4_5() {
    let input = &["KS AH AS AD AC", "4H AH 3H 2H 5H"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["4H AH 3H 2H 5H"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn aces_cannot_be_in_the_middle_of_a_straight_flush_q_k_a_2_3() {
    let input = &["2C AC QC 10C KC", "QH KH AH 2H 3H"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["2C AC QC 10C KC"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn both_hands_have_a_straight_flush_tie_goes_to_highest_ranked_card() {
    let input = &["4H 6H 7H 8H 5H", "5S 7S 8S 9S 6S"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["5S 7S 8S 9S 6S"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}

#[test]
fn even_though_an_ace_is_usually_high_a_5_high_straight_flush_is_the_lowest_scoring_straight_flush()
{
    let input = &["2H 3H 4H 5H 6H", "4D AD 3D 2D 5D"];
    let output = winning_hands(input).into_iter().collect::<HashSet<_>>();
    let expected = ["2H 3H 4H 5H 6H"].into_iter().collect::<HashSet<_>>();
    assert_eq!(output, expected);
}