Refactor tests with data generator. (#5439)

tests/cpp/test_helpers.cc

@@ -0,0 +1,44 @@
+#include <gtest/gtest.h>
+#include <algorithm>
+
+#include "helpers.h"
+namespace xgboost {
+
+TEST(RandomDataGenerator, DMatrix) {
+  size_t constexpr kRows { 16 }, kCols { 32 };
+  float constexpr kSparsity { 0.4f };
+  auto p_dmatrix = RandomDataGenerator{kRows, kCols, kSparsity}.GenerateDMatix();
+
+  HostDeviceVector<float> csr_value;
+  HostDeviceVector<bst_row_t> csr_rptr;
+  HostDeviceVector<bst_feature_t> csr_cidx;
+  RandomDataGenerator{kRows, kCols, kSparsity}.GenerateCSR(&csr_value, &csr_rptr, &csr_cidx);
+
+  HostDeviceVector<float> dense_data;
+  RandomDataGenerator{kRows, kCols, kSparsity}.GenerateDense(&dense_data);
+
+  auto it = std::copy_if(
+      dense_data.HostVector().begin(), dense_data.HostVector().end(),
+      dense_data.HostVector().begin(), [](float v) { return !std::isnan(v); });
+
+  CHECK_EQ(p_dmatrix->Info().num_row_, kRows);
+  CHECK_EQ(p_dmatrix->Info().num_col_, kCols);
+
+  for (auto const& page : p_dmatrix->GetBatches<SparsePage>()) {
+    size_t n_elements = page.data.Size();
+    CHECK_EQ(n_elements, it - dense_data.HostVector().begin());
+    CHECK_EQ(n_elements, csr_value.Size());
+
+    for (size_t i = 0; i < n_elements; ++i) {
+      CHECK_EQ(dense_data.HostVector()[i], csr_value.HostVector()[i]);
+      CHECK_EQ(dense_data.HostVector()[i], page.data.HostVector()[i].fvalue);
+      CHECK_EQ(page.data.HostVector()[i].index, csr_cidx.HostVector()[i]);
+    }
+    CHECK_EQ(page.offset.Size(), csr_rptr.Size());
+    for (size_t i = 0; i < p_dmatrix->Info().num_row_; ++i) {
+      CHECK_EQ(page.offset.HostVector()[i], csr_rptr.HostVector()[i]);
+    }
+  }
+}
+
+}  // namespace xgboost