Add en passant santization tests to the CI and pos is ok

closes https://github.com/official-stockfish/Stockfish/pull/6615

No functional change

src/position.cpp

@@ -1515,6 +1515,23 @@ bool Position::pos_is_ok() const {
     if ((pieces(PAWN) & (Rank1BB | Rank8BB)) || pieceCount[W_PAWN] > 8 || pieceCount[B_PAWN] > 8)
         assert(0 && "pos_is_ok: Pawns");
 
+
+    if (ep_square() != SQ_NONE)
+    {
+        Square ksq = square<KING>(sideToMove);
+
+        Bitboard captured = (ep_square() + pawn_push(~sideToMove)) & pieces(~sideToMove, PAWN);
+        Bitboard pawns    = attacks_bb<PAWN>(ep_square(), ~sideToMove) & pieces(sideToMove, PAWN);
+        Bitboard potentialCheckers = pieces(~sideToMove) ^ captured;
+
+        if (!captured || !pawns
+            || ((attackers_to(ksq, pieces() ^ captured ^ ep_square() ^ lsb(pawns))
+                 & potentialCheckers)
+                && (attackers_to(ksq, pieces() ^ captured ^ ep_square() ^ msb(pawns))
+                    & potentialCheckers)))
+            assert(0 && "pos_is_ok: En passant square");
+    }
+
     if ((pieces(WHITE) & pieces(BLACK)) || (pieces(WHITE) | pieces(BLACK)) != pieces()
         || popcount(pieces(WHITE)) > 16 || popcount(pieces(BLACK)) > 16)
         assert(0 && "pos_is_ok: Bitboards");

tests/instrumented.py

@@ -4,6 +4,7 @@ import sys
 import subprocess
 import pathlib
 import os
+import fnmatch
 
 from testing import (
     EPD,
@@ -474,6 +475,94 @@ class TestSyzygy(metaclass=OrderedClassMembers):
         self.stockfish.check_output(check_output)
         self.stockfish.expect("bestmove *")
 
+class TestEnPassantSanitization(metaclass=OrderedClassMembers):
+    def beforeAll(self):
+        self.stockfish = Stockfish()
+
+    def afterAll(self):
+        self.stockfish.quit()
+        assert self.stockfish.close() == 0
+
+    def afterEach(self):
+        assert postfix_check(self.stockfish.get_output()) == True
+        self.stockfish.clear_output()
+
+    def test_position_1(self):
+        self.stockfish.send_command("position fen rnbqkbnr/ppp1p1pp/5p2/3pP3/8/8/PPPP1PPP/RNBQKBNR w kq d6 0 3")
+        self.stockfish.send_command("d")
+
+        self.stockfish.expect_for_line_matching("Fen*", "*rnbqkbnr/ppp1p1pp/5p2/3pP3/8/8/PPPP1PPP/RNBQKBNR w kq d6 0 3*")
+
+    def test_position_2(self):
+        self.stockfish.send_command("position fen k7/8/8/1pP5/2K5/8/8/8 w - b6 0 1")
+        self.stockfish.send_command("d")
+
+        self.stockfish.expect_for_line_matching("Fen*", "*k7/8/8/1pP5/2K5/8/8/8 w - b6 0 1*")
+
+    def test_position_3(self):
+        self.stockfish.send_command("position fen k1r5/8/8/1pP5/2K5/8/8/8 w - b6 0 1")
+        self.stockfish.send_command("d")
+
+        self.stockfish.expect_for_line_matching("Fen*", "*k1r5/8/8/1pP5/2K5/8/8/8 w - - 0 1*")
+
+    def test_position_4(self):
+        self.stockfish.send_command("position fen k1r5/8/8/1pP5/8/2K5/8/8 w - b6 0 1")
+        self.stockfish.send_command("d")
+
+        self.stockfish.expect_for_line_matching("Fen*", "*k1r5/8/8/1pP5/8/2K5/8/8 w - - 0 1*")
+
+    def test_position_5(self):
+        self.stockfish.send_command("position fen k1r5/8/8/PpP5/8/2K5/8/8 w - b6 0 1")
+        self.stockfish.send_command("d")
+
+        self.stockfish.expect_for_line_matching("Fen*", "*k1r5/8/8/PpP5/8/2K5/8/8 w - b6 0 1*")
+
+    def test_position_6(self):
+        self.stockfish.send_command("position fen k1r5/8/8/PpP5/2K5/8/8/8 w - b6 0 1")
+        self.stockfish.send_command("d")
+
+        self.stockfish.expect_for_line_matching("Fen*", "*k1r5/8/8/PpP5/2K5/8/8/8 w - b6 0 1*")
+
+    def test_position_7(self):
+        self.stockfish.send_command("position fen k7/4b3/8/PpP5/1K6/8/8/8 w - b6 0 1")
+        self.stockfish.send_command("d")
+
+        self.stockfish.expect_for_line_matching("Fen*", "*k7/4b3/8/PpP5/1K6/8/8/8 w - b6 0 1*")
+
+    def test_position_8(self):
+        self.stockfish.send_command("position fen k7/b5b1/8/2PpP3/3K4/8/8/8 w - d6 0 1")
+        self.stockfish.send_command("d")
+
+        self.stockfish.expect_for_line_matching("Fen*", "*k7/b5b1/8/2PpP3/3K4/8/8/8 w - - 0 1*")
+
+    def test_position_9(self):
+        self.stockfish.send_command("position fen k7/8/8/r2pPK2/8/8/8/8 w - d6 0 1")
+        self.stockfish.send_command("d")
+
+        self.stockfish.expect_for_line_matching("Fen*", "*k7/8/8/r2pPK2/8/8/8/8 w - - 0 1*")
+
+    def test_position_10(self):
+        self.stockfish.send_command("position fen k7/8/8/r1PpPK2/8/8/8/8 w - d6 0 1")
+        self.stockfish.send_command("d")
+
+        self.stockfish.expect_for_line_matching("Fen*", "*k7/8/8/r1PpPK2/8/8/8/8 w - d6 0 1*")
+
+    def test_position_11(self):
+        self.stockfish.send_command("position fen kb6/8/8/3pP3/5K2/8/8/8 w - d6 0 1")
+        self.stockfish.send_command("d")
+
+        self.stockfish.expect_for_line_matching("Fen*", "*kb6/8/8/3pP3/5K2/8/8/8 w - d6 0 1*")
+
+    def test_position_find_draw(self):
+        self.stockfish.send_command("position fen q4kb1/3Q2nq/8/r3PpK1/2n5/7q/8/q7 w - f6 0 1 moves d7c8 f8f7 c8d7 f7f8 d7d8 f8f7")
+        self.stockfish.send_command("go nodes 10000")
+
+        def check_output(output):
+            if fnmatch.fnmatch(output, "* score cp 0 * pv d8d7*"):
+                return True
+        
+        self.stockfish.check_output(check_output)
+        self.stockfish.expect("bestmove d8d7*")
 
 def parse_args():
     parser = argparse.ArgumentParser(description="Run Stockfish with testing options")
@@ -508,7 +597,7 @@ if __name__ == "__main__":
     framework = MiniTestFramework()
 
     # Each test suite will be run inside a temporary directory
-    framework.run([TestCLI, TestInteractive, TestSyzygy])
+    framework.run([TestCLI, TestInteractive, TestSyzygy, TestEnPassantSanitization])
 
     EPD.delete_bench_epd()
     TSAN.unset_tsan_option()

tests/testing.py

@@ -126,6 +126,11 @@ class TimeoutException(Exception):
         self.message = message
         self.timeout = timeout
 
+class UnexpectedOutputException(Exception):
+    def __init__(self, actual: str, expected: str):
+        self.actual   = actual
+        self.expected = expected
+
 
 def timeout_decorator(timeout: float):
     def decorator(func):
@@ -230,6 +235,11 @@ class MiniTestFramework:
                     f" {method} (hit execution limit of {e.timeout} seconds)"
                 )
 
+            if isinstance(e, UnexpectedOutputException):
+                self.print_failure(
+                    f" {method} encountered unexpeted output: \"{e.actual}\" when output matching \"{e.expected}\" was expected"
+                )
+
             if isinstance(e, AssertionError):
                 self.__handle_assertion_error(t0, method)
 
@@ -371,6 +381,15 @@ class Stockfish:
             if callback(line) == True:
                 return
 
+    @timeout_decorator(MAX_TIMEOUT)    
+    def expect_for_line_matching(self, line_match: str, expected: str):
+        for line in self.readline():
+            if fnmatch.fnmatch(line, line_match):
+                if fnmatch.fnmatch(line, expected):
+                    break
+                else:
+                    raise UnexpectedOutputException(line, expected)
+
     def readline(self):
         if not self.process:
             raise RuntimeError("Stockfish process is not started")