Macro assert_nth_scalar_is_null 

macro_rules! assert_nth_scalar_is_null {
    ($arr:expr, $n:expr) => { ... };
}

Asserts that the scalar at position $n in array $arr is null.

Example

let arr = PrimitiveArray::from_option_iter([Some(1), None, Some(3)]);
assert_nth_scalar_null!(arr, 1);