All variants of multiplying BigUint by BigDigit

Allow the multiplication to occur with either operand order and with any
combination of owned and borrowed arguments.

bigint/src/biguint.rs

@@ -460,6 +460,8 @@ impl<'a, 'b> Mul<&'b BigUint> for &'a BigUint {
     }
 }
 
+forward_all_scalar_binop_to_val_val!(impl Mul<BigDigit> for BigUint, mul);
+
 impl Mul<BigDigit> for BigUint {
     type Output = BigUint;
 

bigint/src/tests/biguint.rs

@@ -822,13 +822,15 @@ fn test_scalar_mul() {
         if a_vec.len() == 1 {
             let b = BigUint::from_slice(b_vec);
             let a = a_vec[0];
-            assert!(b * a == c);
+            assert_op!(a * b == c);
+            assert_op!(b * a == c);
         }
 
         if b_vec.len() == 1 {
             let a = BigUint::from_slice(a_vec);
             let b = b_vec[0];
-            assert!(a * b == c);
+            assert_op!(a * b == c);
+            assert_op!(b * a == c);
         }
     }
 }