[board] Implement a bunch of sight tests

board/src/position/position.rs

@@ -236,6 +236,12 @@ impl Position {
             .next()
             .unwrap();
         sight_of_opposing_player.is_set(king_square)
+}
+
+#[cfg(test)]
+impl Position {
+    pub(crate) fn test_set_en_passant_square(&mut self, square: Square) {
+        self.en_passant_square = Some(square);
     }
 }
 

board/src/sight.rs

@@ -153,3 +153,108 @@ impl PlacedPiece {
         BitBoard::king_moves(self.square()) & !position.friendly_pieces()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    macro_rules! sight_test {
+        ($test_name:ident, $position:expr, $piece:expr, $bitboard:expr) => {
+            #[test]
+            fn $test_name() {
+                let pos = $position;
+                let pp = $piece;
+                let sight = pp.sight_in_position(&pos);
+
+                assert_eq!(sight, $bitboard);
+            }
+        };
+        ($test_name:ident, $piece:expr, $bitboard:expr) => {
+            sight_test! {$test_name, $crate::Position::empty(), $piece, $bitboard}
+        };
+    }
+
+    mod pawn {
+        use crate::{position, sight::Sight, BitBoard, Position, Square};
+
+        sight_test!(e4_pawn, piece!(White Pawn on E4), bitboard!(D5, F5));
+
+        sight_test!(
+            e4_pawn_one_blocker,
+            position![
+                White Bishop on D5,
+                White Pawn on E4,
+            ],
+            piece!(White Pawn on E4),
+            bitboard!(F5)
+        );
+
+        #[test]
+        fn e4_pawn_two_blocker() {
+            let pos = position!(
+                White Bishop on D5,
+                White Queen on F5,
+                White Pawn on E4,
+            );
+            let pp = piece!(White Pawn on E4);
+            let sight = pp.sight_in_position(&pos);
+
+            assert_eq!(sight, BitBoard::empty());
+        }
+
+        #[test]
+        fn e4_pawn_capturable() {
+            let pos = position!(
+                Black Bishop on D5,
+                White Queen on F5,
+                White Pawn on E4,
+            );
+            let pp = piece!(White Pawn on E4);
+            let sight = pp.sight_in_position(&pos);
+
+            assert_eq!(sight, bitboard!(D5));
+        }
+
+        #[test]
+        fn e5_en_passant() {
+            let mut pos = position!(
+                White Pawn on E5,
+                Black Pawn on D5,
+            );
+            pos.test_set_en_passant_square(Square::D6);
+            let pp = piece!(White Pawn on E5);
+            let sight = pp.sight_in_position(&pos);
+
+            assert_eq!(sight, bitboard!(D6, F6));
+        }
+    }
+
+    #[macro_use]
+    mod knight {
+        use crate::{sight::Sight, Position};
+
+        sight_test!(
+            f6_knight,
+            piece!(Black Knight on F6),
+            bitboard!(H7, G8, E8, D7, D5, E4, G4, H5)
+        );
+    }
+
+    mod bishop {
+        use crate::sight::Sight;
+
+        sight_test!(
+            c2_bishop,
+            piece!(Black Bishop on C2),
+            bitboard!(D1, B3, A4, B1, D3, E4, F5, G6, H7)
+        );
+    }
+
+    mod rook {
+        use crate::sight::Sight;
+
+        sight_test!(
+            g3_rook,
+            piece!(White Rook on G3),
+            bitboard!(G1, G2, G4, G5, G6, G7, G8, A3, B3, C3, D3, E3, F3, H3)
+        );
+    }
+}