modes:pair:tests: refactor for cleanliness

src/modes/pair.rs

@@ -99,16 +99,33 @@ impl PartialOrd for Pair {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::card::{make_decks, Rank};
+    use crate::{
+        card::{make_decks, Rank},
+        modes::tests::test_non_reflexivity,
+    };
 
     #[test]
     fn new() {
         // Two jokers can never be a pair.
         assert_eq!(Pair::new(Card::make_joker(), Card::make_joker()), None);
 
-        for rank in Rank::iter_all() {
-            for c1 in rank.cards() {
-                for c2 in rank.cards() {
+        // Iterate over all ranks
+        for r1 in Rank::iter_all() {
+            // Iterate over all cards in a rank
+            for c1 in r1.cards() {
+                // Iterate over all ranks that aren't r1
+                for r2 in Rank::iter_all().filter(|&r2| r2 != r1) {
+                    // TEST: Cannot compose a pair made from two different
+                    // ranked cards.
+                    let all_cards = r2.cards();
+                    let all_pairs =
+                        all_cards.filter_map(|c2| Pair::new(c1, c2));
+
+                    assert_eq!(all_pairs.count(), 0);
+                }
+
+                // Iterate over all cards that are of the same rank as r1.
+                for c2 in r1.cards() {
                     // TEST: Pairs are composed of two similar rank cards.
                     let pair = {
                         let pair = Pair::new(c1, c2);
@@ -139,52 +156,16 @@ mod tests {
                 assert!(matches!(pair.0, Card::Joker(_)));
                 assert!(matches!(pair.1, Card::PlayingCard(_)));
             }
-
-            for opposing_rank in Rank::iter_all() {
-                if rank == opposing_rank {
-                    continue;
-                }
-
-                assert!(rank != opposing_rank);
-                // TEST: Two playing cards of differing rank can never be a pair.
-                for r1 in rank.cards() {
-                    for r2 in opposing_rank.cards() {
-                        assert_eq!(Pair::new(r1, r2), None);
-                    }
-                }
-            }
         }
     }
 
+    fn exhaustive_pairs_deck() -> impl Iterator<Item = Pair> {
         // A rank has 4 cards.  There are a total of 10 proper pairs that can be
         // made out of 4 cards.  With n jokers, add 4n improper pairs to the
         // total count of pairs for a single rank.
-
-    fn exhaustive_pairs_deck() -> Vec<Pair> {
-        // A deck has 2 jokers => 18 pairs per rank.
-        let mut pairs = Vec::with_capacity(13 * 18);
-        for c1 in make_decks(1) {
-            for c2 in make_decks(2) {
-                if let Some(p) = Pair::new(c1, c2) {
-                    pairs.push(p);
-                }
-            }
-        }
-        pairs
-    }
-
-    fn exhaustive_pairs_rank(r: Rank) -> Vec<Pair> {
-        // We're only looking at one joker here, so 14 pairs in a rank.
-        let mut pairs = Vec::with_capacity(14);
-        for c1 in r.cards() {
-            for c2 in r.cards() {
-                pairs.push(Pair::new(c1, c2).unwrap());
-            }
-
-            pairs.push(Pair::new(c1, Card::make_joker()).unwrap());
-        }
-
-        pairs
+        make_decks(1).flat_map(|c1| {
+            make_decks(1).filter_map(move |c2| Pair::new(c1, c2))
+        })
     }
 
     #[test]
@@ -203,32 +184,31 @@ mod tests {
                 // exclusively one of the pairs is improper - pairs that are
                 // improper should be sorted less than the proper one.
                 (Ordering::Less, Ordering::Equal) => {
-                    // p1 has a joker, p2 doesn't => p2 is better than p1
+                    // p1 has a joker, p2 doesn't => p1 < p2
                     p1.is_improper() && p2.is_proper()
                 }
                 (Ordering::Greater, Ordering::Equal) => {
-                    // p2 has a joker, p1 doesn't => p1 is better than p2
+                    // p2 has a joker, p1 doesn't => p1 > p2
                     p2.is_improper() && p1.is_proper()
                 }
                 _ => false,
             }
         }
 
-        for p1 in &exhaustive_pairs_deck() {
-            for p2 in &exhaustive_pairs_deck() {
+        for p1 in exhaustive_pairs_deck() {
+            for p2 in exhaustive_pairs_deck() {
                 // TEST: For any two pair we expect them to have the
                 // `expected_ordering_relation`.
-                assert!(expected_ordering_relation(p1, p2));
+                assert!(expected_ordering_relation(&p1, &p2));
             }
         }
     }
 
     #[test]
     fn footstool() {
-        let pairs = exhaustive_pairs_deck();
-        for p1 in &pairs {
-            for p2 in &pairs {
-                let (p1_on_p2, p2_on_p1) = test_non_reflexivity(p1, p2);
+        for p1 in exhaustive_pairs_deck() {
+            for p2 in exhaustive_pairs_deck() {
+                let (p1_on_p2, p2_on_p1) = test_non_reflexivity(&p1, &p2);
                 let (hc1_on_hc2, hc2_on_hc1) = {
                     let [high_card_1, high_card_2] =
                         [p1.1, p2.1].map(Single::new).map(|x| {