test(plugin25): verify nextCards result

Author: xeruf

plugin2025/src/main/kotlin/sc/plugin2025/GameState.kt

@@ -122,6 +122,14 @@ data class GameState @JvmOverloads constructor(
             ExchangeCarrots(-10).takeIf { mayExchangeCarrots(-10, player) },
         )
 
+    /** Checks which cards of the given player are usable from its current position.
+     * Does not check validity of a whole move.
+     *
+     * Usable means playable on a hare field
+     * and buyable on a market field.
+     *
+     * @return empty array means no cards are usable,
+     * null means not on a field where cards can be used. */
     fun nextCards(player: Hare = currentPlayer): Collection<Array<Card>>? =
         when(player.field) {
             Field.HARE -> {

plugin2025/src/test/kotlin/sc/plugin2025/CardTest.kt

@@ -2,6 +2,7 @@ package sc.plugin2025
 
 import io.kotest.core.spec.style.FunSpec
 import io.kotest.matchers.*
+import io.kotest.matchers.collections.*
 import sc.plugin2025.util.HuIConstants
 
 class CardTest: FunSpec({
@@ -13,10 +14,13 @@ class CardTest: FunSpec({
             lastSalad shouldBe HuIConstants.LAST_SALAD
             state.currentPlayer.position = lastSalad!!
             Card.SWAP_CARROTS.check(state) shouldBe HuIMoveMistake.CANNOT_PLAY_SWAP_CARROTS_BEYOND_LAST_SALAD
-            state.currentPlayer.position = lastSalad - 1
+            state.currentPlayer.position = state.board.getPreviousField(Field.HARE, lastSalad)!!
             Card.SWAP_CARROTS.check(state) shouldBe null
+            state.currentPlayer.addCard(Card.SWAP_CARROTS)
+            state.nextCards() shouldContainExactly listOf(arrayOf(Card.SWAP_CARROTS))
             state.otherPlayer.position = lastSalad
             Card.SWAP_CARROTS.check(state) shouldBe HuIMoveMistake.CANNOT_PLAY_SWAP_CARROTS_BEYOND_LAST_SALAD
+            state.nextCards().shouldBeEmpty()
         }
         state.currentPlayer.addCard(Card.SWAP_CARROTS)
         test("not repeatable") {