feat: add display to Sum

01.workspace/oxydice_lib/src/imp/mod.rs

@@ -2,3 +2,4 @@ pub mod dice_grab;
 pub mod dice_roll;
 pub mod dice_sum;
 pub mod die_roll;
+pub mod sum_display;

01.workspace/oxydice_lib/src/imp/sum_display.rs

@@ -0,0 +1,17 @@
+use crate::*;
+
+impl fmt::Display for Sum {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        let str_results: Vec<String> = self
+            .roll_results
+            .iter()
+            .map(|r| r.checked_add(1))
+            .map(|o| o.unwrap_or(0))
+            .map(|r| r.to_string())
+            .collect();
+        write!(f, "{}", format!("[{}]", str_results.join(", ")))?;
+        write!(f, " -> ")?;
+        write!(f, "{}", self.sum)?;
+        Ok(())
+    }
+}

01.workspace/oxydice_lib/src/tst/mod.rs

@@ -2,3 +2,4 @@ pub mod dice_grab;
 pub mod dice_roll;
 pub mod dice_sum;
 pub mod die_roll;
+pub mod sum_display;

01.workspace/oxydice_lib/src/tst/sum_display.rs

@@ -0,0 +1,9 @@
+#[cfg(test)]
+mod tests {
+    use crate::*;
+    #[test]
+    pub fn sum_display_format_should_be_correct() {
+        let result = Dice::grab(3, 1).roll().sum().unwrap();
+        assert_eq!(&result.to_string(), "[1, 1, 1] -> 3");
+    }
+}