add tests

Signed-off-by: Matt Katz <mhkatz97@gmail.com>

Author: mhk197

vortex-array/src/arrays/decimal/compute/mod.rs

@@ -20,6 +20,7 @@ mod tests {
     use crate::compute::conformance::binary_numeric::test_binary_numeric_array;
     use crate::compute::conformance::consistency::test_array_consistency;
     use crate::dtype::DecimalDType;
+    use crate::dtype::NativeDecimalType;
     use crate::validity::Validity;
 
     #[rstest]
@@ -83,6 +84,14 @@ mod tests {
         DecimalDType::new(5, 1),
         Validity::NonNullable,
     ))]
+    #[case::decimal_widened_carry(DecimalArray::new(
+        buffer![
+            <i128 as NativeDecimalType>::MAX_BY_PRECISION[38],
+            <i128 as NativeDecimalType>::MIN_BY_PRECISION[38],
+        ],
+        DecimalDType::new(38, 0),
+        Validity::NonNullable,
+    ))]
     #[case::decimal_single(DecimalArray::new(
         buffer![42i128],
         DecimalDType::new(10, 0),

vortex-array/src/compute/conformance/binary_numeric.rs

@@ -25,6 +25,8 @@ use std::fmt::Debug;
 
 use itertools::Itertools;
 use num_traits::Bounded;
+use num_traits::CheckedAdd;
+use num_traits::CheckedSub;
 use num_traits::Float;
 use num_traits::Num;
 use num_traits::Signed;
@@ -328,14 +330,19 @@ fn test_decimal_binary_numeric_with_scalar(
                     let (Some(lhs), Some(rhs)) = (lhs.decimal_value(), rhs.decimal_value()) else {
                         return Some(Scalar::null(result_dtype.clone()));
                     };
+                    let lhs = lhs.as_i256();
+                    let rhs = rhs.as_i256();
                     let value = match operator {
                         NumericOperator::Add => lhs.checked_add(&rhs),
                         NumericOperator::Sub => lhs.checked_sub(&rhs),
                         NumericOperator::Mul | NumericOperator::Div => unreachable!(),
                     }?;
-                    value.fits_in_precision(result_decimal_dtype).then(|| {
-                        Scalar::decimal(value, result_decimal_dtype, result_dtype.nullability())
-                    })
+                    let value = DecimalValue::try_from_i256(value, result_decimal_dtype).ok()?;
+                    Some(Scalar::decimal(
+                        value,
+                        result_decimal_dtype,
+                        result_dtype.nullability(),
+                    ))
                 })
                 .collect();
 

vortex-array/src/scalar_fn/fns/binary/numeric/tests.rs

@@ -342,13 +342,13 @@ fn test_decimal_overflow_on_null_lane_ignored() {
 fn test_decimal_add_reserves_carry_digit() {
     let mut ctx = array_session().create_execution_ctx();
     let dtype = DecimalDType::new(2, 0);
-    let lhs = DecimalArray::from_iter::<i8, _>([60], dtype).into_array();
-    let rhs = DecimalArray::from_iter::<i8, _>([60], dtype).into_array();
+    let lhs = DecimalArray::from_iter::<i8, _>([99], dtype).into_array();
+    let rhs = DecimalArray::from_iter::<i8, _>([99], dtype).into_array();
 
     let result = decimal_binary(lhs, rhs, Operator::Add).unwrap();
     assert_arrays_eq!(
         result,
-        DecimalArray::from_iter::<i16, _>([120], DecimalDType::new(3, 0)),
+        DecimalArray::from_iter::<i16, _>([198], DecimalDType::new(3, 0)),
         &mut ctx
     );
 }