add a unit test that cover cast bug. (#5443)

datafusion/physical-expr/src/expressions/cast.rs

@@ -689,4 +689,20 @@ mod tests {
  }
  Ok(())
  }
+
+ #[test]
+ #[ignore] // TODO: https://github.com/apache/arrow-datafusion/issues/5396
+ fn test_cast_decimal() -> Result<()> {
+ let schema = Schema::new(vec![Field::new("a", DataType::Int64, false)]);
+ let a = Int64Array::from(vec![100]);
+ let batch = RecordBatch::try_new(Arc::new(schema.clone()), vec![Arc::new(a)])?;
+ let expression = cast_with_options(
+ col("a", &schema)?,
+ &schema,
+ DataType::Decimal128(38, 38),
+ DEFAULT_DATAFUSION_CAST_OPTIONS,
+ )?;
+ expression.evaluate(&batch)?;
+ Ok(())
+ }
 }