I think it's working again

*wipes brow* thank god.

src/game.rs

@@ -119,9 +119,11 @@ impl Piece {
         }
     }
 
-    fn moves_at(&self, from: &BoardIndex) -> Vec<BoardIndex> {
-        self.moves().map(|(x, y)| {
-            *from + (*x, *y)
+    fn moves_at(&self, from: &BoardIndex) -> HashSet<BoardIndex> {
+        self.moves().filter_map(|(x, y)| {
+            let bi = *from + (*x, *y);
+            // Check if this goes out of bounds, if so exclude from the list of possible moves
+            (bi.x <= 7 && bi.y <= 3).then_some(bi)
         })
         .collect()
     }
@@ -287,8 +289,8 @@ impl std::ops::Add<(isize, isize)> for BoardIndex {
 
     fn add(self, (a, b): (isize, isize)) -> Self {
         BoardIndex {
-            x: self.x.saturating_add_signed(a).max(7),
-            y: self.y.saturating_add_signed(b).max(3),
+            x: self.x.saturating_add_signed(a),
+            y: self.y.saturating_add_signed(b),
         }
     }
 }
@@ -298,8 +300,8 @@ impl std::ops::Add<(usize, usize)> for BoardIndex {
 
     fn add(self, (a, b): (usize, usize)) -> Self {
         BoardIndex {
-            x: self.x.saturating_add(a).max(7),
-            y: self.y.saturating_add(b).max(3),
+            x: self.x.saturating_add(a),
+            y: self.y.saturating_add(b),
         }
     }
 }
@@ -538,7 +540,7 @@ impl Board {
             .moves_at(&from)
             .iter()
             // Find if the given `to` move is one of those
-            .find(|BoardIndex { x, y }| to == from + (*x, *y))
+            .find(|idx| to == **idx)
             // Determine if this is valid/legal in this situation
             .and_then(|_| {
                 let dest_at = self.at(to);
@@ -798,6 +800,16 @@ mod test {
             );
         }
     }
+
+    #[test]
+    fn test_piece_moves_at() {
+        let given = Piece::Drone.moves_at(&(4, 1).into());
+        let expected: HashSet<BoardIndex> = HashSet::from([
+            (4, 0).into(), (2, 1).into(), (3, 1).into(), (5, 1).into(), (6, 1).into(), (4, 2).into(), (4, 3).into(),
+        ]);
+
+        assert_eq!(expected, given, "Drone moves at");
+    }
 }
 
 impl std::fmt::Display for Board {