[core] Fix the coordinate tests

Use symbols instead of magic numbers.

core/src/coordinates.rs

@@ -433,7 +433,7 @@ impl From<File> for char {
 
 impl From<Rank> for char {
     fn from(value: Rank) -> Self {
-        Self::from(value.0)
+        Self::from(value.0 + b'1')
     }
 }
 
@@ -473,41 +473,39 @@ mod tests {
     #[test]
     fn good_algebraic_input() -> Result<(), ParseSquareError> {
         let sq = Square::from_algebraic_str("a4")?;
-        assert_eq!(sq.file(), File(0));
-        assert_eq!(sq.rank(), Rank(3));
+        assert_eq!(sq.file(), File::A);
+        assert_eq!(sq.rank(), Rank::FOUR);
 
         let sq = Square::from_algebraic_str("B8")?;
-        assert_eq!(sq.file(), File(1));
-        assert_eq!(sq.rank(), Rank(7));
+        assert_eq!(sq.file(), File::B);
+        assert_eq!(sq.rank(), Rank::EIGHT);
 
         let sq = Square::from_algebraic_str("e4")?;
-        assert_eq!(sq.file(), File(4));
-        assert_eq!(sq.rank(), Rank(3));
+        assert_eq!(sq.file(), File::E);
+        assert_eq!(sq.rank(), Rank::FOUR);
 
         Ok(())
     }
 
     #[test]
-    fn bad_algebraic_input() -> Result<(), ParseSquareError> {
-        Square::from_algebraic_str("a0")?;
-        Square::from_algebraic_str("j3")?;
-        Square::from_algebraic_str("a11")?;
-        Square::from_algebraic_str("b-1")?;
-        Square::from_algebraic_str("a 1")?;
-        Square::from_algebraic_str("")?;
-
-        Ok(())
+    fn bad_algebraic_input() {
+        assert!(Square::from_algebraic_str("a0").is_err());
+        assert!(Square::from_algebraic_str("j3").is_err());
+        assert!(Square::from_algebraic_str("a11").is_err());
+        assert!(Square::from_algebraic_str("b-1").is_err());
+        assert!(Square::from_algebraic_str("a 1").is_err());
+        assert!(Square::from_algebraic_str("").is_err());
     }
 
     #[test]
     fn from_index() -> Result<(), ()> {
         let sq = Square::try_from(4u32)?;
-        assert_eq!(sq.file(), File(4));
-        assert_eq!(sq.rank(), Rank(0));
+        assert_eq!(sq.file(), File::E);
+        assert_eq!(sq.rank(), Rank::ONE);
 
         let sq = Square::try_from(28u32)?;
-        assert_eq!(sq.file(), File(4));
-        assert_eq!(sq.rank(), Rank(3));
+        assert_eq!(sq.file(), File::E);
+        assert_eq!(sq.rank(), Rank::FOUR);
 
         Ok(())
     }
@@ -560,5 +558,13 @@ mod tests {
         assert_eq!(format!("{}", Square::C5), "c5");
         assert_eq!(format!("{}", Square::A1), "a1");
         assert_eq!(format!("{}", Square::H8), "h8");
+        assert_eq!(format!("{}", Rank::FIVE), "5");
+        assert_eq!(format!("{}", File::H), "h");
+    }
+
+    #[test]
+    fn into_char() {
+        assert_eq!(Into::<char>::into(Rank::ONE), '1');
+        assert_eq!(Into::<char>::into(File::B), 'b');
     }
 }