error handing for Colour

src/colour.rs

@@ -5,16 +5,23 @@ pub struct Colour {
     pub blue: u8,
 }
 
-impl From<String> for Colour {
+#[derive(Debug)]
+pub struct InvalidRgb;
+
+impl Colour {
     #[inline]
-    fn from(string: String) -> Colour {
+    pub(crate) fn from(string: String) -> Result<Colour, InvalidRgb> {
         let values: Vec<&str> = string.split(',').collect();
 
+        if values.len() != 3 {
+            return Err(InvalidRgb);
+        }
+
         let red: u8 = values[0].parse().unwrap_or(0);
         let green: u8 = values[1].parse().unwrap_or(0);
         let blue: u8 = values[2].parse().unwrap_or(0);
 
-        Colour { red, green, blue }
+        Ok(Colour { red, green, blue })
     }
 }
 
@@ -32,7 +39,7 @@ mod test {
     #[test]
     fn test_colour_from_string() {
         assert_eq!(
-            Colour::from("0,255,0".to_string()),
+            Colour::from("0,255,0".to_string()).unwrap(),
             Colour { red: 0, green: 255, blue: 0 }
         );
     }

src/palette.rs

@@ -23,7 +23,7 @@ impl From<String> for Palette {
 
         let colours = lines[colour_start_index..]
             .iter()
-            .map(|&line| Colour::from(line.to_string()))
+            .map(|&line| Colour::from(line.to_string()).unwrap())
             .collect();
 
         Palette { id, name, colours }