[board] Implement fmt::Display on Square

Prints the square in algebraic notation

board/src/square.rs

@@ -1,6 +1,6 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use std::str::FromStr;
+use std::{fmt, str::FromStr};
 
 pub enum Direction {
     North,
@@ -156,6 +156,12 @@ impl FromStr for Square {
     }
 }
 
+impl fmt::Display for Square {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}{}", ('a' as u8 + self.file) as char, self.rank + 1)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -263,4 +269,11 @@ mod tests {
         assert!(square63.neighbor(Direction::NorthEast).is_none());
         assert!(square63.neighbor(Direction::East).is_none());
     }
+
+    #[test]
+    fn display() {
+        assert_eq!(format!("{}", Square::c5()), "c5");
+        assert_eq!(format!("{}", Square::a1()), "a1");
+        assert_eq!(format!("{}", Square::h8()), "h8");
+    }
 }

board/src/tests.rs

@@ -36,4 +36,5 @@ impl Square {
     sq_constructor!(f6);
     sq_constructor!(g3);
     sq_constructor!(g5);
+    sq_constructor!(h8);
 }