Feature weights (#5962)

tests/cpp/common/test_common.cc

@@ -0,0 +1,13 @@
+#include <gtest/gtest.h>
+#include "../../../src/common/common.h"
+
+namespace xgboost {
+namespace common {
+TEST(ArgSort, Basic) {
+  std::vector<float> inputs {3.0, 2.0, 1.0};
+  auto ret = ArgSort<bst_feature_t>(inputs);
+  std::vector<bst_feature_t> sol{2, 1, 0};
+  ASSERT_EQ(ret, sol);
+}
+}  // namespace common
+}  // namespace xgboost