add unit test temporarily

cpp/tests/groupby/mean_tests.cpp

@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include <cmath>
 #include <cudf/detail/aggregation/aggregation.hpp>
 #include <cudf/utilities/traits.hpp>
 
@@ -160,5 +161,63 @@ TEST_F(groupby_dictionary_mean_test, basic)
     keys, vals, expect_keys, expect_vals, cudf::make_mean_aggregation<groupby_aggregation>());
 }
 
+struct groupby_corr_test : public cudf::test::BaseFixture {
+};
+template <typename T>
+using fwcw    = fixed_width_column_wrapper<T>;
+using structs = structs_column_wrapper;
+
+TEST_F(groupby_corr_test, basic)
+{
+  using K  = int32_t;
+  using M0 = uint8_t;
+  using M1 = int16_t;
+  using R  = cudf::detail::target_type_t<M0, aggregation::CORR>;
+
+  // clang-format off
+  auto keys     = fwcw<K>  { 1,    2,    3,    1,    2,    2,    1,    3,    3,    2  };
+  auto member_0 = fwcw<M0>{{ 1,    1,    1,    2,    2,    3,    3,    1,    1,    4  }};//, null_at(1)};
+  auto member_1 = fwcw<M1>{{ 1,    1,    1,    2,   -2,    3,    3,    1,    1,   -4 }};//, null_at(7)};
+  auto values   = structs{{member_0, member_1}};//, null_at(4)};
+  // clang-format on
+
+  fixed_width_column_wrapper<K> expect_keys({1, 2, 3});
+  fixed_width_column_wrapper<R, double> expect_vals{
+    {1.000000, -0.41522739926869984, std::numeric_limits<double>::quiet_NaN()}};  //, null_at(2)};
+  // clang-format on
+
+  auto agg = cudf::make_corr_aggregation<groupby_aggregation>();
+  std::vector<groupby::aggregation_request> requests;
+  requests.emplace_back(groupby::aggregation_request());
+  requests[0].values = values;
+
+  requests[0].aggregations.push_back(std::move(agg));
+  requests.emplace_back(groupby::aggregation_request());
+  // WAR to force groupby to use sort implementation
+  requests[0].aggregations.push_back(make_nth_element_aggregation<groupby_aggregation>(0));
+
+  requests[1].values = column_view(values).child(0);
+  requests[1].aggregations.push_back(cudf::make_mean_aggregation<groupby_aggregation>());
+  requests[1].aggregations.push_back(cudf::make_std_aggregation<groupby_aggregation>());
+  requests.emplace_back(groupby::aggregation_request());
+  requests[2].values = column_view(values).child(1);
+  requests[2].aggregations.push_back(cudf::make_mean_aggregation<groupby_aggregation>());
+  requests[2].aggregations.push_back(cudf::make_std_aggregation<groupby_aggregation>());
+
+  groupby::groupby gb_obj(table_view({keys}));
+  auto result = gb_obj.aggregate(requests);
+
+  cudf::test::print(*result.second[0].results[0]);
+  cudf::test::print(*result.second[1].results[0]);
+  cudf::test::print(*result.second[1].results[1]);
+  cudf::test::print(*result.second[2].results[0]);
+  cudf::test::print(*result.second[2].results[1]);
+
+  CUDF_TEST_EXPECT_TABLES_EQUAL(table_view({expect_keys}), result.first->view());
+  CUDF_TEST_EXPECT_COLUMNS_EQUIVALENT(
+    expect_vals, *result.second[0].results[0], debug_output_level::ALL_ERRORS);
+  // test_single_agg(keys, values, expect_keys, expect_vals, std::move(agg));
+}
+
 }  // namespace test
 }  // namespace cudf