[position] Fix all the unit tests

The pawn move generator only generated pushes for white pawns.
The is_king_in_check returned an inverted flag.
MoveSet needed a couple more validation methods: can_move_to_square and can_castle.
The MakeMoveBuilder also needed a little more move validation using the above methods.

position/src/position/builders/move_builder.rs

@@ -1,6 +1,10 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use crate::{position::flags::Flags, r#move::Castle, MakeMoveError, Move, Position};
+use crate::{
+    position::flags::Flags,
+    r#move::{AlgebraicMoveFormatter, Castle},
+    MakeMoveError, Move, Position,
+};
 use chessfriend_bitboard::BitBoard;
 use chessfriend_core::{Color, Direction, Piece, PlacedPiece, Shape, Square};
 
@@ -60,9 +64,22 @@ where
 
         let to_square = mv.to_square();
 
-        let sight = self.position.sight_of_piece(&piece);
-        if !sight.is_set(to_square) {
-            return Err(MakeMoveError::IllegalSquare(to_square));
+        let moves = self
+            .position
+            .moves_for_piece(&piece)
+            .ok_or(MakeMoveError::NoLegalMoves)?;
+
+        match mv.castle() {
+            Some(castle) => {
+                if !moves.can_castle(castle) {
+                    return Err(MakeMoveError::IllegalCastle);
+                }
+            }
+            None => {
+                if !moves.can_move_to_square(to_square) {
+                    return Err(MakeMoveError::IllegalSquare(to_square));
+                }
+            }
         }
 
         let player = self.position.player_to_move();
@@ -324,7 +341,7 @@ mod tests {
         assert!(black_pawn_move.is_double_push());
         assert!(!black_pawn_move.is_en_passant());
 
-        let en_passant_position = Builder::<NoMove>::new(&pos).make(&black_pawn_move)?.build();
+        let en_passant_position = Builder::new(&pos).make(&black_pawn_move)?.build();
         println!("{en_passant_position}");
 
         assert_eq!(

position/src/position/position.rs

@@ -2,8 +2,8 @@
 
 use super::{flags::Flags, piece_sets::PieceBitBoards, Pieces};
 use crate::{
-    check::{self, CheckingPieces},
-    move_generator::Moves,
+    check::CheckingPieces,
+    move_generator::{MoveSet, Moves},
     position::DiagramFormatter,
     r#move::Castle,
     sight::SightExt,
@@ -216,6 +216,10 @@ impl Position {
             .fold(BitBoard::empty(), |acc, sight| acc | sight)
     }
 
+    pub(crate) fn moves_for_piece(&self, piece: &PlacedPiece) -> Option<&MoveSet> {
+        self.moves().moves_for_piece(piece)
+    }
+
     pub(crate) fn sight_of_piece(&self, piece: &PlacedPiece) -> BitBoard {
         piece.sight(&self.pieces, self.en_passant_square)
     }
@@ -236,7 +240,7 @@ impl Position {
 
     pub(crate) fn is_king_in_check(&self) -> bool {
         let danger_squares = self.king_danger(self.color_to_move);
-        (danger_squares & self.king_bitboard(self.color_to_move)).is_empty()
+        !(danger_squares & self.king_bitboard(self.color_to_move)).is_empty()
     }
 
     fn king_bitboard(&self, player: Color) -> &BitBoard {