Merge #240

240: Fix is_multiple_of with a 0 arg r=cuviper a=cuviper

See also: rust-num/num-integer#47

Co-authored-by: Josh Stone <cuviper@gmail.com>

src/biguint.rs

@@ -283,6 +283,9 @@ impl Integer for BigUint {
     /// Returns `true` if the number is a multiple of `other`.
     #[inline]
     fn is_multiple_of(&self, other: &BigUint) -> bool {
+        if other.is_zero() {
+            return self.is_zero();
+        }
         (self % other).is_zero()
     }
 

tests/bigint.rs

@@ -1036,6 +1036,18 @@ fn test_lcm() {
     check(11, 5, 55);
 }
 
+#[test]
+fn test_is_multiple_of() {
+    assert!(BigInt::from(0).is_multiple_of(&BigInt::from(0)));
+    assert!(BigInt::from(6).is_multiple_of(&BigInt::from(6)));
+    assert!(BigInt::from(6).is_multiple_of(&BigInt::from(3)));
+    assert!(BigInt::from(6).is_multiple_of(&BigInt::from(1)));
+
+    assert!(!BigInt::from(42).is_multiple_of(&BigInt::from(5)));
+    assert!(!BigInt::from(5).is_multiple_of(&BigInt::from(3)));
+    assert!(!BigInt::from(42).is_multiple_of(&BigInt::from(0)));
+}
+
 #[test]
 fn test_next_multiple_of() {
     assert_eq!(

tests/biguint.rs

@@ -1085,6 +1085,18 @@ fn test_lcm() {
     check(99, 17, 1683);
 }
 
+#[test]
+fn test_is_multiple_of() {
+    assert!(BigUint::from(0u32).is_multiple_of(&BigUint::from(0u32)));
+    assert!(BigUint::from(6u32).is_multiple_of(&BigUint::from(6u32)));
+    assert!(BigUint::from(6u32).is_multiple_of(&BigUint::from(3u32)));
+    assert!(BigUint::from(6u32).is_multiple_of(&BigUint::from(1u32)));
+
+    assert!(!BigUint::from(42u32).is_multiple_of(&BigUint::from(5u32)));
+    assert!(!BigUint::from(5u32).is_multiple_of(&BigUint::from(3u32)));
+    assert!(!BigUint::from(42u32).is_multiple_of(&BigUint::from(0u32)));
+}
+
 #[test]
 fn test_next_multiple_of() {
     assert_eq!(