test(decimal cast): add tests for positive and negative overflow when…

… casting Decimal256 to Float64
apache · alamb · Jul 23, 2025 · Jul 9, 2025 · Jul 9, 2025 · Jul 9, 2025
commit 05ace0c53dea226d38ab6cd5eb8b923a2725f65a
diff --git a/arrow-cast/src/cast/mod.rs b/arrow-cast/src/cast/mod.rs
@@ -8675,13 +8675,25 @@ mod tests {
     }
     #[test]
     fn test_cast_decimal256_to_f64_overflow() {
+        // Test positive overflow (positive infinity)
         let array = vec![Some(i256::MAX)];
         let array = create_decimal256_array(array, 76, 2).unwrap();
         let array = Arc::new(array) as ArrayRef;
 
         let result = cast(&array, &DataType::Float64).unwrap();
         let result = result.as_primitive::<Float64Type>();
         assert!(result.value(0).is_infinite());
+        assert!(result.value(0) > 0.0); // Positive infinity
+
+        // Test negative overflow (negative infinity)
+        let array = vec![Some(i256::MIN)];
+        let array = create_decimal256_array(array, 76, 2).unwrap();
+        let array = Arc::new(array) as ArrayRef;
+
+        let result = cast(&array, &DataType::Float64).unwrap();
+        let result = result.as_primitive::<Float64Type>();
+        assert!(result.value(0).is_infinite());
+        assert!(result.value(0) < 0.0); // Negative infinity
     }
 
     #[test]