Function AssertFirstLastIsNull

cpp/src/arrow/compute/kernels/aggregate_test.cc:1577–1603

template <typename ArrowType>
class TestFirstLastKernel : public ::testing::Test {
  using Traits = TypeTraits<ArrowType>;
  using ArrayType = typename Traits::ArrayType;
  using c_type = typename ArrowType::c_type;
  using ScalarType = typename Traits::ScalarType;

 public:
  void AssertFirstLastIs(const Datum& array, c_type expected_first, c_type expected_last,
                         const ScalarAggregateOptions& options) {
    ASSERT_OK_AND_ASSIGN(Datum out, CallFunction("first", {array}, &options));
    const auto& out_first = out.scalar_as<ScalarType>();
    ASSERT_EQ(expected_first, out_first.value);

    ASSERT_OK_AND_ASSIGN(out, CallFunction("last", {array}, &options));
    const auto& out_last = out.scalar_as<ScalarType>();
    ASSERT_EQ(expected_last, out_last.value);
  }

  void AssertFirstLastIsNull(const Datum& array, const ScalarAggregateOptions& options) {
    ASSERT_OK_AND_ASSIGN(Datum out, First(array, options));
    const auto& out_first = out.scalar_as<ScalarType>();
    ASSERT_FALSE(out_first.is_valid);

    ASSERT_OK_AND_ASSIGN(out, Last(array, options));
    const auto& out_last = out.scalar_as<ScalarType>();
    ASSERT_FALSE(out_last.is_valid);
  }

  void AssertFirstLastIsNull(const std::string& json,
                             const ScalarAggregateOptions& options) {