Fix salad card bug (#87)

* fix: eat salad card usable without salads

* add: test for fix

* add: a modified logic for testing

* fix: broken test

* remove: the modifed the test logic

src/plugin/action/card.rs

@@ -79,7 +79,15 @@ impl Card {
                 // saturating add is here unnecessary because the board is finite and never larger than usize::MAX
                 self.move_to_field(current, state, other.position + 1, remaining_cards)?;
             }
-            Card::EatSalad => current.eat_salad(state)?,
+            Card::EatSalad => {
+                if current.salads == 0 {
+                    return Err(HUIError::new_err(
+                        "You can only play this card if you have lettuce left",
+                    ));
+                }
+
+                current.eat_salad(state)?
+            }
             Card::SwapCarrots => {
                 if current.position >= PluginConstants::LAST_LETTUCE_POSITION
                     || other.position >= PluginConstants::LAST_LETTUCE_POSITION

src/plugin/test/card_test.rs

@@ -147,4 +147,16 @@ mod tests {
         let result = invalid_card.perform(&mut state, vec![Card::EatSalad, Card::SwapCarrots]);
         assert!(result.is_err());
     }
+
+    #[test]
+    fn test_no_salad_but_salad_card() {
+        let mut state = create_test_game_state();
+        let card = Card::EatSalad;
+        let mut current_player = state.clone_current_player();
+        current_player.salads = 0;
+        current_player.cards = vec![card];
+        state.update_player(current_player);
+        let result = card.perform(&mut state, vec![]);
+        assert!(result.is_err());
+    }
 }