Fix default metric configuration. (#9575)

tests/cpp/objective_helpers.cc

@@ -0,0 +1,31 @@
+/**
+ * Copyright (c) 2023, XGBoost contributors
+ */
+#include "objective_helpers.h"
+
+#include "../../src/common/linalg_op.h"  // for begin, end
+#include "helpers.h"                     // for RandomDataGenerator
+
+namespace xgboost {
+std::shared_ptr<DMatrix> MakeFmatForObjTest(std::string const& obj) {
+  auto constexpr kRows = 10, kCols = 10;
+  auto p_fmat = RandomDataGenerator{kRows, kCols, 0}.GenerateDMatrix(true);
+  auto& h_upper = p_fmat->Info().labels_upper_bound_.HostVector();
+  auto& h_lower = p_fmat->Info().labels_lower_bound_.HostVector();
+  h_lower.resize(kRows);
+  h_upper.resize(kRows);
+  for (size_t i = 0; i < kRows; ++i) {
+    h_lower[i] = 1;
+    h_upper[i] = 10;
+  }
+  if (obj.find("rank:") != std::string::npos) {
+    auto h_label = p_fmat->Info().labels.HostView();
+    std::size_t k = 0;
+    for (auto& v : h_label) {
+      v = k % 2 == 0;
+      ++k;
+    }
+  }
+  return p_fmat;
+};
+}  // namespace xgboost