wrong indexes panic test

src/matrix.rs

@@ -67,6 +67,7 @@ impl IndexMut<(usize, usize)> for Matrix {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use std::panic;
     #[test]
     fn simple_matrix() {
         assert_eq!(
@@ -93,6 +94,15 @@ mod tests {
         let m2 = Matrix::new(3, 2, vec![int!(1), int!(2), int!(3), int!(4), int!(5), int!(6)]).unwrap();
         assert_eq!(m2[(0, 2)], int!(3));
         assert_eq!(m2[(1, 0)], int!(4));
+        let result = panic::catch_unwind(|| {
+            let _ = m2[(0, 3)];
+        });
+        assert!(result.is_err(), "Expected panic on m2[(0, 3)]");
+
+        let result2 = panic::catch_unwind(|| {
+            let _ = m2[(2, 0)];
+        });
+        assert!(result2.is_err(), "Expected panic on m2[(2, 0)]");
     }
 
     #[test]