Fix negation with overflow (paupino#657)

benschulz · Paul Mason · web-flow · commit 6f7d295cd825 · 2024-04-11T15:56:27.000Z
* Fix negation with overflow
* Extend scope of tests to remove blindness
---------

Co-authored-by: Paul Mason &lt;paul@salsa.dev&gt;
diff --git a/src/decimal.rs b/src/decimal.rs
@@ -1990,7 +1990,7 @@ impl FromPrimitive for Decimal {
             unsigned = n as u128;
             flags = 0;
         } else {
-            unsigned = -n as u128;
+            unsigned = n.unsigned_abs();
             flags = SIGN_MASK;
         };
         // Check if we overflow
diff --git a/tests/decimal_tests.rs b/tests/decimal_tests.rs
@@ -2967,11 +2967,18 @@ fn it_converts_from_i128() {
         (92233720368547758089, Some("92233720368547758089")),
         (0xFFFF_FFFF_FFFF_FFFF_FFFF_FFFF, Some("79228162514264337593543950335")),
         (0x7FFF_FFFF_FFFF_FFFF_FFFF_FFFF_FFFF_FFFF, None),
+        (i128::MIN, None),
+        (i128::MAX, None),
     ];
     for (value, expected) in tests {
-        if let Some(expected_value) = expected {
-            let decimal = Decimal::from_str(expected_value).unwrap();
-            assert_eq!(num_traits::FromPrimitive::from_i128(*value), Some(decimal));
+        let from_i128 = num_traits::FromPrimitive::from_i128(*value);
+
+        match expected {
+            Some(expected_value) => {
+                let decimal = Decimal::from_str(expected_value).unwrap();
+                assert_eq!(from_i128, Some(decimal));
+            }
+            None => assert!(from_i128.is_none()),
         }
     }
 }
@@ -2983,11 +2990,17 @@ fn it_converts_from_u128() {
         (0xFFFF_FFFF_FFFF_FFFF, Some("18446744073709551615")),
         (0xFFFF_FFFF_FFFF_FFFF_FFFF_FFFF, Some("79228162514264337593543950335")),
         (0x7FFF_FFFF_FFFF_FFFF_FFFF_FFFF_FFFF_FFFF, None),
+        (u128::MAX, None),
     ];
     for (value, expected) in tests {
-        if let Some(expected_value) = expected {
-            let decimal = Decimal::from_str(expected_value).unwrap();
-            assert_eq!(num_traits::FromPrimitive::from_u128(*value), Some(decimal));
+        let from_u128 = num_traits::FromPrimitive::from_u128(*value);
+
+        match expected {
+            Some(expected_value) => {
+                let decimal = Decimal::from_str(expected_value).unwrap();
+                assert_eq!(from_u128, Some(decimal));
+            }
+            None => assert!(from_u128.is_none()),
         }
     }
 }
