test: add unit test for arrow_cast function to validate casting to Float64 and Int32

Author: kosiew

python/tests/test_functions.py

@@ -905,6 +905,18 @@ def test_temporal_functions(df):
     )
 
 
+def test_arrow_cast(df):
+    df = df.select(
+        f.arrow_cast(column("a"), "Float64").alias("a_as_float"),
+        f.arrow_cast(column("a"), "Int32").alias("a_as_int"),
+    )
+    result = df.collect()
+    assert len(result) == 1
+    result = result[0]
+    assert result.column(0) == pa.array([1.0, 2.0, 3.0], type=pa.float64())
+    assert result.column(1) == pa.array([1, 2, 3], type=pa.int32())
+
+
 def test_case(df):
     df = df.select(
         f.case(column("b")).when(literal(4), literal(10)).otherwise(literal(8)),

src/functions.rs

@@ -384,8 +384,8 @@ macro_rules! expr_fn {
     ($FUNC: ident, $($arg:ident)*, $DOC: expr) => {
         #[doc = $DOC]
         #[pyfunction]
-        fn $FUNC($($arg: PyExpr),*, data_type: &str) -> PyExpr {
-            functions::expr_fn::$FUNC($($arg.into()),*, data_type.to_string()).into()
+        fn $FUNC($($arg: PyExpr),*) -> PyExpr {
+            functions::expr_fn::$FUNC($($arg.into()),*).into()
         }
     };
 }
@@ -563,7 +563,7 @@ expr_fn_vec!(r#struct); // Use raw identifier since struct is a keyword
 expr_fn_vec!(named_struct);
 expr_fn!(from_unixtime, unixtime);
 expr_fn!(arrow_typeof, arg_1);
-expr_fn!(arrow_cast, expr data_type);
+expr_fn!(arrow_cast, datatype);
 expr_fn!(random);
 
 // Array Functions