Castling bug (all variants) about dartchess HOT 2 OPEN

I'm not sure to understand what is the bug here. _getCastlingSide() is a private method and by itself it doesn't generate "legal" castling moves.
Legality is tested using unit tests and especially perft tests, and afaik there is no bug detected here.

I saw your PR so I'll try to look at it, but in general issues should be raised when you find a bug with the public API of dartchess with a test proving sth is wrong that I can reproduce.

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Hi Vincent!

That makes sense. Let me try again.

Take a classical game of chess at this fen:

r3k2r/pppbbppp/2n2n2/3pp2Q/3PP2q/2N2N2/PPPBBPPP/R3K2R w KQkq - 10 8

It's white's move and if you query whether or not e1a2 is a legal move...

position.isLegal(NormalMove(from: 4, to: 8))

it returns true. In fact all of these are considered legal moves:

e1e1, e1a2, e1b2, e1c2, e1d2, e1e2, e1f2, e1g2, e1h2, e1c3, e1f3, e1d4, e1e4, e1h5

If you play the move e1a2 (or any of these options), White castles.

And on the next move, it's the same situation for Black.

e8h4, e8d5, e8e5, e8c6, e8f6, e8a7, e8b7, e8c7, e8d7, e8e7, e8f7, e8g7, e8h7, e8e8 are all considered legal.

In my pull request, the tests for this setup start at line 90 of position_test.dart.

The cause of this bug is in _getCastlingSide(), which I provided a fix for in my pull request. And that's why I titled my issue that way.

Thanks for your patience with me and helping me understand the proper way to communicate here.

Have a great day!

Kind regards,
David

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