test(search): add search and move-ordering heuristic tests

tests/Search.test.scala

@@ -0,0 +1,29 @@
+package gambit
+
+class SearchTest extends munit.FunSuite:
+
+  private def mateThreshold = Searcher.MateValue - 100
+
+  test("finds mate in 1 for white") {
+    val pos = Fen.parse("6k1/5ppp/8/8/8/8/8/R6K w - - 0 1")
+    val (move, score) = new Searcher().bestMove(pos, 3)
+    assertEquals(Move.uci(move), "a1a8")
+    assert(score >= mateThreshold, s"expected mate score, got $score")
+  }
+
+  test("finds mate in 1 for black") {
+    val pos = Fen.parse("r6k/8/8/8/8/8/5PPP/6K1 b - - 0 1")
+    val (move, score) = new Searcher().bestMove(pos, 3)
+    assertEquals(Move.uci(move), "a8a1")
+    assert(score >= mateThreshold, s"expected mate score, got $score")
+  }
+
+  test("captures the hanging queen") {
+    val pos = Fen.parse("4k3/8/8/8/8/8/3q4/4K1R1 w - - 0 1")
+    val (move, _) = new Searcher().bestMove(pos, 3)
+    assertEquals(Move.to(move), Square.make(3, 1))
+  }
+
+  test("evaluation is symmetric on start position") {
+    assertEquals(Eval.evaluate(Fen.parse(Fen.startPosition)), 0)
+  }