diff --git a/tests/cpp/tree/test_approx.cc b/tests/cpp/tree/test_approx.cc
index 4eb049cdb170..57a0cd3545bb 100644
--- a/tests/cpp/tree/test_approx.cc
+++ b/tests/cpp/tree/test_approx.cc
@@ -8,19 +8,6 @@
 
 namespace xgboost {
 namespace tree {
-namespace {
-void GetSplit(RegTree *tree, float split_value, std::vector<CPUExpandEntry> *candidates) {
-  tree->ExpandNode(
-      /*nid=*/RegTree::kRoot, /*split_index=*/0, /*split_value=*/split_value,
-      /*default_left=*/true, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,
-      /*left_sum=*/0.0f,
-      /*right_sum=*/0.0f);
-  candidates->front().split.split_value = split_value;
-  candidates->front().split.sindex = 0;
-  candidates->front().split.sindex |= (1U << 31);
-}
-}  // anonymous namespace
-
 TEST(Approx, Partitioner) {
   size_t n_samples = 1024, n_features = 1, base_rowid = 0;
   ApproxRowPartitioner partitioner{n_samples, base_rowid};
@@ -33,18 +20,20 @@ TEST(Approx, Partitioner) {
   ctx.InitAllowUnknown(Args{});
   std::vector<CPUExpandEntry> candidates{{0, 0, 0.4}};
 
-  auto grad = GenerateRandomGradients(n_samples);
-  std::vector<float> hess(grad.Size());
-  std::transform(grad.HostVector().cbegin(), grad.HostVector().cend(), hess.begin(),
-                 [](auto gpair) { return gpair.GetHess(); });
-
-  for (auto const &page : Xy->GetBatches<GHistIndexMatrix>({GenericParameter::kCpuId, 64, hess})) {
-    bst_feature_t const split_ind = 0;
+  for (auto const &page : Xy->GetBatches<GHistIndexMatrix>({GenericParameter::kCpuId, 64})) {
+    bst_feature_t split_ind = 0;
     {
       auto min_value = page.cut.MinValues()[split_ind];
       RegTree tree;
+      tree.ExpandNode(
+          /*nid=*/0, /*split_index=*/0, /*split_value=*/min_value,
+          /*default_left=*/true, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,
+          /*left_sum=*/0.0f,
+          /*right_sum=*/0.0f);
       ApproxRowPartitioner partitioner{n_samples, base_rowid};
-      GetSplit(&tree, min_value, &candidates);
+      candidates.front().split.split_value = min_value;
+      candidates.front().split.sindex = 0;
+      candidates.front().split.sindex |= (1U << 31);
       partitioner.UpdatePosition(&ctx, page, candidates, &tree);
       ASSERT_EQ(partitioner.Size(), 3);
       ASSERT_EQ(partitioner[1].Size(), 0);
@@ -55,8 +44,16 @@ TEST(Approx, Partitioner) {
       auto ptr = page.cut.Ptrs()[split_ind + 1];
       float split_value = page.cut.Values().at(ptr / 2);
       RegTree tree;
-      GetSplit(&tree, split_value, &candidates);
+      tree.ExpandNode(
+          /*nid=*/RegTree::kRoot, /*split_index=*/split_ind,
+          /*split_value=*/split_value,
+          /*default_left=*/true, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,
+          /*left_sum=*/0.0f,
+          /*right_sum=*/0.0f);
       auto left_nidx = tree[RegTree::kRoot].LeftChild();
+      candidates.front().split.split_value = split_value;
+      candidates.front().split.sindex = 0;
+      candidates.front().split.sindex |= (1U << 31);
       partitioner.UpdatePosition(&ctx, page, candidates, &tree);
 
       auto elem = partitioner[left_nidx];