[board] Implement TryFrom<&str> for Shape

Convert a string to a Shape using the first character in the string.
Rename TryFromCharError → TryFromError

board/src/piece.rs

@@ -1,8 +1,7 @@
 // Eryn Wells <eryn@erynwells.me>
 
-use std::fmt;
-
 use crate::Square;
+use std::fmt;
 
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 pub enum Color {
@@ -58,10 +57,11 @@ impl Shape {
     }
 }
 
-pub struct TryFromCharError;
+#[derive(Debug, Eq, PartialEq)]
+pub struct TryFromError;
 
 impl TryFrom<char> for Shape {
-    type Error = TryFromCharError;
+    type Error = TryFromError;
 
     fn try_from(value: char) -> Result<Self, Self::Error> {
         match value {
@@ -71,11 +71,20 @@ impl TryFrom<char> for Shape {
             'R' => Ok(Shape::Rook),
             'Q' => Ok(Shape::Queen),
             'K' => Ok(Shape::King),
-            _ => Err(TryFromCharError),
+            _ => Err(TryFromError),
         }
     }
 }
 
+impl TryFrom<&str> for Shape {
+    type Error = TryFromError;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        let first_char = value.chars().nth(0).ok_or(TryFromError)?;
+        Shape::try_from(first_char)
+    }
+}
+
 impl Into<char> for &Shape {
     fn into(self) -> char {
         self._ascii_representation()
@@ -147,3 +156,19 @@ impl PlacedPiece {
         PlacedPiece { piece, square }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn shape_try_from() {
+        assert_eq!(Shape::try_from('p'), Ok(Shape::Pawn));
+        assert_eq!(Shape::try_from("p"), Ok(Shape::Pawn));
+    }
+
+    #[test]
+    fn shape_into_char() {
+        assert_eq!(<Shape as Into<char>>::into(Shape::Pawn) as char, 'p');
+    }
+}