feat(core): add Card, Suit, Rank types with tests

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_core/src/card.rs

@@ -0,0 +1,121 @@
+use serde::{Deserialize, Serialize};
+
+/// Card suit.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
+pub enum Suit {
+    Clubs,
+    Diamonds,
+    Hearts,
+    Spades,
+}
+
+impl Suit {
+    /// Returns `true` for red suits (Diamonds, Hearts).
+    pub fn is_red(self) -> bool {
+        matches!(self, Suit::Diamonds | Suit::Hearts)
+    }
+
+    /// Returns `true` for black suits (Clubs, Spades).
+    pub fn is_black(self) -> bool {
+        !self.is_red()
+    }
+}
+
+/// Card rank, Ace through King.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
+pub enum Rank {
+    Ace,
+    Two,
+    Three,
+    Four,
+    Five,
+    Six,
+    Seven,
+    Eight,
+    Nine,
+    Ten,
+    Jack,
+    Queen,
+    King,
+}
+
+impl Rank {
+    /// Numeric value: Ace = 1, King = 13.
+    pub fn value(self) -> u8 {
+        match self {
+            Rank::Ace   => 1,
+            Rank::Two   => 2,
+            Rank::Three => 3,
+            Rank::Four  => 4,
+            Rank::Five  => 5,
+            Rank::Six   => 6,
+            Rank::Seven => 7,
+            Rank::Eight => 8,
+            Rank::Nine  => 9,
+            Rank::Ten   => 10,
+            Rank::Jack  => 11,
+            Rank::Queen => 12,
+            Rank::King  => 13,
+        }
+    }
+}
+
+/// A single playing card.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct Card {
+    pub id: u32,
+    pub suit: Suit,
+    pub rank: Rank,
+    pub face_up: bool,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn rank_value_ace_is_one() {
+        assert_eq!(Rank::Ace.value(), 1);
+    }
+
+    #[test]
+    fn rank_value_king_is_thirteen() {
+        assert_eq!(Rank::King.value(), 13);
+    }
+
+    #[test]
+    fn rank_values_are_sequential() {
+        let ranks = [
+            Rank::Ace, Rank::Two, Rank::Three, Rank::Four, Rank::Five,
+            Rank::Six, Rank::Seven, Rank::Eight, Rank::Nine, Rank::Ten,
+            Rank::Jack, Rank::Queen, Rank::King,
+        ];
+        for (i, r) in ranks.iter().enumerate() {
+            assert_eq!(r.value(), (i + 1) as u8);
+        }
+    }
+
+    #[test]
+    fn suit_red_is_diamonds_and_hearts() {
+        assert!(Suit::Diamonds.is_red());
+        assert!(Suit::Hearts.is_red());
+        assert!(!Suit::Clubs.is_red());
+        assert!(!Suit::Spades.is_red());
+    }
+
+    #[test]
+    fn suit_black_is_clubs_and_spades() {
+        assert!(Suit::Clubs.is_black());
+        assert!(Suit::Spades.is_black());
+        assert!(!Suit::Diamonds.is_black());
+        assert!(!Suit::Hearts.is_black());
+    }
+
+    #[test]
+    fn card_face_up_field_reflects_construction() {
+        let card = Card { id: 0, suit: Suit::Hearts, rank: Rank::Ace, face_up: false };
+        assert!(!card.face_up);
+        let card2 = Card { id: 1, suit: Suit::Spades, rank: Rank::King, face_up: true };
+        assert!(card2.face_up);
+    }
+}