add test and derive clone

src/array/primitive/mutable.rs

@@ -14,7 +14,7 @@ use super::PrimitiveArray;
 
 /// The Arrow's equivalent to `Vec<Option<T>>` where `T` is byte-size (e.g. `i32`).
 /// Converting a [`MutablePrimitiveArray`] into a [`PrimitiveArray`] is `O(1)`.
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct MutablePrimitiveArray<T: NativeType> {
     data_type: DataType,
     values: Vec<T>,

src/bitmap/mutable.rs

@@ -14,6 +14,7 @@ use super::Bitmap;
 /// The main difference against [`Vec<bool>`] is that a bitmap cannot be represented as `&[bool]`.
 /// # Implementation
 /// This container is backed by [`Vec<u8>`].
+#[derive(Clone)]
 pub struct MutableBitmap {
     buffer: Vec<u8>,
     // invariant: length.saturating_add(7) / 8 == buffer.len();

tests/it/array/primitive/mutable.rs

@@ -270,6 +270,12 @@ fn set_validity() {
     a.extend_trusted_len(vec![Some(1), Some(2)].into_iter());
     let validity = a.validity().unwrap();
     assert_eq!(validity.null_count(), 0);
+
+    // test that upon conversion to array the bitmap is set to None
+    let arr: PrimitiveArray<_> = a.clone().into();
+    assert_eq!(arr.validity(), None);
+
+    // test set_validity
     a.set_validity(Some(MutableBitmap::from([false, true])));
     assert_eq!(a.validity(), Some(&MutableBitmap::from([false, true])));
 }