test(movegen): add move generation and perft tests

tests/MoveGen.test.scala

@@ -0,0 +1,49 @@
+package gambit
+
+class MoveGenTest extends munit.FunSuite:
+
+  private def legal(fen: String): Vector[Int] =
+    val moves = new MoveList()
+    MoveGen.generateLegal(Fen.parse(fen), moves)
+    (0 until moves.size).map(moves.apply).toVector
+
+  test("en passant generated in matching position") {
+    val moves = legal("rnbqkbnr/ppp1pppp/8/3pP3/8/8/PPPP1PPP/RNBQKBNR w KQkq d6 0 3")
+    val ep = moves.filter(Move.isEnPassant)
+    assertEquals(ep.size, 1)
+    assertEquals(Move.uci(ep.head), "e5d6")
+  }
+
+  test("both castling moves generated when legal") {
+    val moves = legal("r3k2r/8/8/8/8/8/8/R3K2R w KQkq - 0 1")
+    val castles = moves.filter(Move.isCastle).map(Move.uci).toSet
+    assertEquals(castles, Set("e1g1", "e1c1"))
+  }
+
+  test("castling blocked when king passes through check") {
+    val moves = legal("r3k2r/8/8/8/8/8/6q1/R3K2R w KQkq - 0 1")
+    val castles = moves.filter(Move.isCastle).map(Move.uci).toSet
+    assertEquals(castles, Set("e1c1"))
+  }
+
+  test("promotions generated with all four pieces") {
+    val moves = legal("8/P7/8/8/8/8/8/k6K w - - 0 1")
+    val promos = moves.filter(Move.isPromotion).map(Move.uci).toSet
+    assertEquals(promos, Set("a7a8q", "a7a8r", "a7a8b", "a7a8n"))
+  }
+
+  test("pinned knight cannot move") {
+    val moves = legal("4r2k/8/8/8/8/8/4N3/4K3 w - - 0 1")
+    val knightMoves = moves.filter(m => Move.from(m) == Square.make(4, 1))
+    assertEquals(knightMoves.size, 0)
+  }
+
+  test("only check evasions when in check") {
+    val moves = legal("4k3/8/8/8/8/8/8/r3K2R w K - 0 1")
+    assert(moves.nonEmpty)
+    for m <- moves do
+      val pos = Fen.parse("4k3/8/8/8/8/8/8/r3K2R w K - 0 1")
+      val undo = pos.make(m)
+      assert(!pos.isAttacked(pos.kingSquare(Color.White), Color.Black), s"illegal ${Move.uci(m)}")
+      pos.unmake(m, undo)
+  }

tests/Perft.test.scala

@@ -0,0 +1,34 @@
+package gambit
+
+class PerftTest extends munit.FunSuite:
+  val kiwipete = "r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq - 0 1"
+  val position3 = "8/2p5/3p4/KP5r/1R3p1k/8/4P1P1/8 w - - 0 1"
+  val position4 = "r3k2r/Pppp1ppp/1b3nbN/nP6/BBP1P3/q4N2/Pp1P2PP/R2Q1RK1 w kq - 0 1"
+  val position5 = "rnbq1k1r/pp1Pbppp/2p5/8/2B5/8/PPP1NnPP/RNBQK2R w KQ - 1 8"
+  val position6 = "r4rk1/1pp1qppp/p1np1n2/2b1p1B1/2B1P1b1/P1NP1N2/1PP1QPPP/R4RK1 w - - 0 10"
+
+  def perft(fen: String, depth: Int): Long = Perft.perft(Fen.parse(fen), depth)
+
+  test("startpos perft 1") { assertEquals(perft(Fen.startPosition, 1), 20L) }
+  test("startpos perft 2") { assertEquals(perft(Fen.startPosition, 2), 400L) }
+  test("startpos perft 3") { assertEquals(perft(Fen.startPosition, 3), 8902L) }
+  test("startpos perft 4") { assertEquals(perft(Fen.startPosition, 4), 197281L) }
+
+  test("kiwipete perft 1") { assertEquals(perft(kiwipete, 1), 48L) }
+  test("kiwipete perft 2") { assertEquals(perft(kiwipete, 2), 2039L) }
+  test("kiwipete perft 3") { assertEquals(perft(kiwipete, 3), 97862L) }
+  test("kiwipete perft 4") { assertEquals(perft(kiwipete, 4), 4085603L) }
+
+  test("position3 perft 4") { assertEquals(perft(position3, 4), 43238L) }
+  test("position3 perft 5") { assertEquals(perft(position3, 5), 674624L) }
+
+  test("position4 perft 3") { assertEquals(perft(position4, 3), 9467L) }
+  test("position4 perft 4") { assertEquals(perft(position4, 4), 422333L) }
+
+  test("position5 perft 1") { assertEquals(perft(position5, 1), 44L) }
+  test("position5 perft 2") { assertEquals(perft(position5, 2), 1486L) }
+  test("position5 perft 3") { assertEquals(perft(position5, 3), 62379L) }
+  test("position5 perft 4") { assertEquals(perft(position5, 4), 2103487L) }
+
+  test("position6 perft 3") { assertEquals(perft(position6, 3), 89890L) }
+  test("position6 perft 4") { assertEquals(perft(position6, 4), 3894594L) }

tests/PerftSlow.test.scala

@@ -0,0 +1,33 @@
+package gambit
+
+class PerftSlowTest extends munit.FunSuite:
+  override val munitTimeout = scala.concurrent.duration.Duration(120, "s")
+
+  val kiwipete = "r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq - 0 1"
+  val position3 = "8/2p5/3p4/KP5r/1R3p1k/8/4P1P1/8 w - - 0 1"
+  val position4 = "r3k2r/Pppp1ppp/1b3nbN/nP6/BBP1P3/q4N2/Pp1P2PP/R2Q1RK1 w kq - 0 1"
+  val position5 = "rnbq1k1r/pp1Pbppp/2p5/8/2B5/8/PPP1NnPP/RNBQK2R w KQ - 1 8"
+
+  test("startpos perft 5") {
+    assertEquals(Perft.perft(Fen.parse(Fen.startPosition), 5), 4865609L)
+  }
+
+  test("startpos perft 6") {
+    assertEquals(Perft.perft(Fen.parse(Fen.startPosition), 6), 119060324L)
+  }
+
+  test("kiwipete perft 5") {
+    assertEquals(Perft.perft(Fen.parse(kiwipete), 5), 193690690L)
+  }
+
+  test("position3 perft 6") {
+    assertEquals(Perft.perft(Fen.parse(position3), 6), 11030083L)
+  }
+
+  test("position4 perft 5") {
+    assertEquals(Perft.perft(Fen.parse(position4), 5), 15833292L)
+  }
+
+  test("position5 perft 5") {
+    assertEquals(Perft.perft(Fen.parse(position5), 5), 89941194L)
+  }