Fri, 04 Sep 2026 13:49:48 +0200
add function to reconstruct a board from a FEN string
resolves #939 in principle, but there are many TODOs left
/* * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. * * Copyright 2026 Mike Becker. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * */ #include "chess/fen.h" #include "ucxtest.h" static CX_TEST(test_fen_basic) { /* a test that simply checks if an arbitrary FEN is parsed correctly */ const char * fen = "r1n3k1/5qbp/p5p1/1p6/4Q3/B6P/P4PP1/R4RK1 b - - 0 27"; Board expected_board = { {WROOK, 0, 0, 0, 0, WROOK, WKING, 0}, {WPAWN, 0, 0, 0, 0, WPAWN, WPAWN, 0}, {WBISHOP, 0, 0, 0, 0, 0, 0, WPAWN}, {0, 0, 0, 0, WQUEEN, 0, 0, 0}, {0, BPAWN, 0, 0, 0, 0, 0, 0}, {BPAWN, 0, 0, 0, 0, 0, BPAWN, 0}, {0, 0, 0, 0, 0, BQUEEN, BBISHOP, BPAWN}, {BROOK, 0, BKNIGHT, 0, 0, 0, BKING, 0} }; GameState gs; int result = fen_parse(fen, &gs); CX_TEST_DO { CX_TEST_ASSERT(result == 0); CX_TEST_ASSERT(strcmp(gs.fen_start, fen) == 0); /* counter for fifty-move rule initialized with zero */ CX_TEST_ASSERT(gs.fifty_cntr_start == 0); /* we start after 53 half-moves have been played */ CX_TEST_ASSERT(gs.move_start == 53); /* we have no move history */ CX_TEST_ASSERT(gs.movecount == 0); CX_TEST_ASSERT(gs.movecapacity == 0); CX_TEST_ASSERT(gs.moves == NULL); CX_TEST_ASSERT(gs.fen == NULL); /* all castling rights should be revoked */ CX_TEST_ASSERT(gs.castling.K == true); CX_TEST_ASSERT(gs.castling.Q == true); CX_TEST_ASSERT(gs.castling.k == true); CX_TEST_ASSERT(gs.castling.q == true); /* check the board */ for (File f = 0 ; f < 8 ; f++) { for (Rank r = 0 ; r < 8 ; r++) { Piece exp = expected_board[r][f]; Piece p = piece_at(&gs, f, r); char msg[64]; sprintf(msg, "expected %u at %c:%c but got %u", exp, filechr(f), rankchr(r), p); CX_TEST_ASSERTM(exp == p, msg); } } /* check that other stuff is empty-initialized */ CX_TEST_ASSERT(gs.bname[0] == 0); CX_TEST_ASSERT(gs.wname[0] == 0); CX_TEST_ASSERT(gs.premove[0] == 0); CX_TEST_ASSERT(!gs.checkmate); CX_TEST_ASSERT(!gs.stalemate); CX_TEST_ASSERT(!gs.threefold); CX_TEST_ASSERT(!gs.nomaterial); CX_TEST_ASSERT(!gs.remis); CX_TEST_ASSERT(!gs.wresign); CX_TEST_ASSERT(!gs.bresign); CX_TEST_ASSERT(!gs.ragequit); CX_TEST_ASSERT(!gs.review); /* check that we get the original FEN back */ char fen_chk[FEN_MAX_LENGTH]; fen_compute(fen_chk, &gs); CX_TEST_ASSERTM(strcmp(fen, fen_chk) == 0, fen_chk); } gamestate_cleanup(&gs); } CxTestSuite* test_fen_suite(void) { CxTestSuite* suite = cx_test_suite_new("Test FEN API"); cx_test_register(suite, test_fen_basic); // TODO: test FENs that describe definitely ended games (for each type of ending) // TODO: test FEN that comes with a non-zero fifty-move rule counter // TODO: test FEN with en-passant threat return suite; }