More tests.

tests/it/ffi.rs

@@ -1,13 +1,12 @@
 use arrow2::array::*;
+use arrow2::bitmap::Bitmap;
 use arrow2::datatypes::{DataType, Field, TimeUnit};
 use arrow2::{error::Result, ffi};
 use std::collections::BTreeMap;
 use std::sync::Arc;
 
-fn test_round_trip(expected: impl Array + Clone + 'static) -> Result<()> {
-    let array: Arc<dyn Array> = Arc::new(expected.clone());
+fn _test_round_trip(array: Arc<dyn Array>, expected: Box<dyn Array>) -> Result<()> {
     let field = Field::new("a", array.data_type().clone(), true);
-    let expected = Box::new(expected) as Box<dyn Array>;
 
     let array_ptr = Box::new(ffi::Ffi_ArrowArray::empty());
     let schema_ptr = Box::new(ffi::Ffi_ArrowSchema::empty());
@@ -32,6 +31,15 @@ fn test_round_trip(expected: impl Array + Clone + 'static) -> Result<()> {
     Ok(())
 }
 
+fn test_round_trip(expected: impl Array + Clone + 'static) -> Result<()> {
+    let array: Arc<dyn Array> = Arc::new(expected.clone());
+    let expected = Box::new(expected) as Box<dyn Array>;
+    _test_round_trip(array.clone(), clone(expected.as_ref()))?;
+
+    // sliced
+    _test_round_trip(array.slice(1, 2).into(), expected.slice(1, 2))
+}
+
 fn test_round_trip_schema(field: Field) -> Result<()> {
     // create a `ArrowArray` from the data.
     let schema_ptr = Box::new(ffi::Ffi_ArrowSchema::empty());
@@ -138,6 +146,17 @@ fn list_list() -> Result<()> {
     test_round_trip(array)
 }
 
+#[test]
+fn struct_() -> Result<()> {
+    let data_type = DataType::Struct(vec![Field::new("a", DataType::Int32, true)]);
+    let values = vec![Arc::new(Int32Array::from([Some(1), None, Some(3)])) as Arc<dyn Array>];
+    let validity = Bitmap::from([true, false, true]);
+
+    let array = StructArray::from_data(data_type, values, validity.into());
+
+    test_round_trip(array)
+}
+
 #[test]
 fn dict() -> Result<()> {
     let data = vec![Some("a"), Some("a"), None, Some("b")];