tip/test/test-fen.c

/*
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 * Copyright 2026 Mike Becker. All rights reserved.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#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;
}