test that subtraction appropriately panics

diff --git a/solutions/src/bigint.rs b/solutions/src/bigint.rs
index 7a61b4b5de9ccfac4a6dc717145055f181a88494..8d67a78efe5267a88930302292714ccad451da89 100644 (file)
--- a/solutions/src/bigint.rs
+++ b/solutions/src/bigint.rs
@@ -320,12 +320,24 @@ mod tests {
 
         assert_eq!(&b2 - &b1, BigInt::from_vec(vec![u64::max_value() - (1 << 32) + 1]));
         assert_eq!(&b3 - &b2, BigInt::from_vec(vec![0, u64::max_value(), 0]));
-        assert_eq!(&b2 - &b4 - &b4, BigInt::from_vec(vec![0]));
+        assert_eq!(&b2 - &b4 - &b4, BigInt::new(0));
         assert_eq!(&b3 - &b2 - &b4 - &b4, BigInt::from_vec(vec![0, u64::max_value() - 1]));
         assert_eq!(&b3 - &b4 - &b2 - &b4, BigInt::from_vec(vec![0, u64::max_value() - 1]));
         assert_eq!(&b3 - &b4 - &b4 - &b2, BigInt::from_vec(vec![0, u64::max_value() - 1]));
     }
 
+    #[test]
+    #[should_panic(expected = "Wrapping subtraction of BigInt")]
+    fn test_sub_panic1() {
+        let _ = BigInt::new(1) - BigInt::new(5);
+    }
+
+    #[test]
+    #[should_panic(expected = "Wrapping subtraction of BigInt")]
+    fn test_sub_panic2() {
+        let _ = BigInt::from_vec(vec![5,8,3,33,1<<13,46,1<<49, 1, 583,1<<60,2533]) - BigInt::from_vec(vec![5,8,3,33,1<<13,46,1<<49, 5, 583,1<<60,2533]);
+    }
+
     #[test]
     fn test_inc1() {
         let mut b = BigInt::new(0);