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modes:single:tests: refactor footstool_deck_irrelevance via a combinatory argument

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This commit is contained in:
Aryadev Chavali
2026-04-07 01:57:28 +01:00
committed by oreodave
parent a1d0d72b1e
commit 9b1db4382d
1 changed files with 52 additions and 56 deletions
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108
src/modes/single.rs
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@@ -213,67 +213,63 @@ mod tests {
#[test] #[test]
fn footstool_deck_irrelevance() { fn footstool_deck_irrelevance() {
// For a fixed Single, comparing to another deck's cards doesn't change /*
// if it gets footstooled. A combinatorial check should be satisfactory here, given the extensive
let pivot = PlayingCard::new(0, Rank::Three, Suit::Club); testing of in-deck footstools from the previous test. I'll create a
formula for the number of footstools we should expect to see from an
exhaustive checking of all Singles in N decks of cards where N > 0.
for i in 1..10 { For 1 deck there are 51 cards that have 1 half footstool and 1 full
let piv_copy = PlayingCard::new(i, pivot.rank, pivot.suit); footstool, and 1 card (3[D]) which has 1 full footstool. This gave us
let piv_before = piv_copy 103 by (51 * 2) + 1.
.prev()
.and_then(|x| Some(Card::PlayingCard(x)))
.and_then(|x| Some(Single(x)))
.unwrap();
let piv_after = piv_copy
.next()
.and_then(|x| Some(Card::PlayingCard(x)))
.and_then(|x| Some(Single(x)))
.unwrap();
let piv_way_after = piv_copy
.next()
.and_then(|x| x.next())
.and_then(|x| Some(Card::PlayingCard(x)))
.and_then(|x| Some(Single(x)))
.unwrap();
let piv_copy = Card::PlayingCard(piv_copy);
let piv_copy = Single(piv_copy);
let pivot = Card::PlayingCard(pivot);
let pivot = Single(pivot);
// TEST: a single may be footstooled by a single from another deck For n decks, there will be (51*n) cards that have n choices for full
// with the same rank and suit. footstool and n choices for half footstool. The remaing n cards will
let (piv_on_piv_copy, _) = test_footstool(&pivot, &piv_copy); all be 3[D], which means they will only get n full footstools.
assert_eq!(
piv_on_piv_copy,
Footstool::Full,
"Expected {pivot}, {piv_copy} to full footstool."
);
// TEST: A single may be half footstooled by singles from another Another way to look at it is (52 * n * n) half footstools and (51 * n *
// deck. n) full footstools. So (51 + 52) * (n * n) => 103n^2 footstools in n
let (piv_on_piv_before, _) = test_footstool(&pivot, &piv_before); decks.
assert_eq!( */
piv_on_piv_before,
Footstool::Half,
"Expected {pivot}, {piv_before} to half footstool."
);
let (_, piv_after_on_piv) = test_footstool(&pivot, &piv_after); const N_DECKS: usize = 10;
assert_eq!(
piv_after_on_piv,
Footstool::Half,
"Expected {pivot}, {piv_after} to half footstool."
);
// TEST: A single is still not footstooled by singles from other // Function which maps a Footstool to a usize for use in array indexing.
// decks that aren't adjacent. fn footstool_to_numeral(f: Footstool) -> usize {
let (piv_on_piv_way_after, _) = match f {
test_footstool(&pivot, &piv_way_after); Footstool::None => 0,
assert_eq!( Footstool::Half => 1,
piv_on_piv_way_after, Footstool::Full => 2,
Footstool::None, }
"Expected {pivot}, {piv_way_after} to not footstool."
);
} }
// Create a map that counts all the footstools possible between all
// cards.
let counter = {
let mut counter = [0; 3];
// Iterator over Cards from N_DECKS number of decks.
let cards = (0..((N_DECKS as i64) * 52)).map(Card::from);
cards
.clone()
.flat_map(move |c1| cards.clone().map(move |c2| (c1, c2)))
.for_each(|(c1, c2)| {
let res = test_footstool(&Single(c1), &Single(c2)).0;
let res = footstool_to_numeral(res);
counter[res] += 1;
});
counter
};
let [_, half, full] = counter;
// TEST: There are 103n^2 footstool instances.
assert_eq!(103 * N_DECKS * N_DECKS, half + full);
// TEST: There are 51n^2 half footstool instances.
assert_eq!(51 * N_DECKS * N_DECKS, half);
// TEST: There are 52n^2 full footstool instances.
assert_eq!(52 * N_DECKS * N_DECKS, full);
} }
} }