Remove leaf vector, add tree serialisation test, fix Windows tests (#3989)

tests/cpp/tree/test_tree_model.cc

@@ -0,0 +1,87 @@
+// Copyright by Contributors
+#include <gtest/gtest.h>
+#include <xgboost/tree_model.h>
+#include "../helpers.h"
+#include "dmlc/filesystem.h"
+
+namespace xgboost {
+// Manually construct tree in binary format
+// Do not use structs in case they change
+// We want to preserve backwards compatibility
+TEST(Tree, Load) {
+  dmlc::TemporaryDirectory tempdir;
+  const std::string tmp_file = tempdir.path + "/tree.model";
+  std::unique_ptr<dmlc::Stream> fo(dmlc::Stream::Create(tmp_file.c_str(), "w"));
+
+  // Write params
+  EXPECT_EQ(sizeof(TreeParam), (31 + 6) * sizeof(int));
+  int num_roots = 1;
+  int num_nodes = 2;
+  int num_deleted = 0;
+  int max_depth = 1;
+  int num_feature = 0;
+  int size_leaf_vector = 0;
+  int reserved[31];
+  fo->Write(&num_roots, sizeof(int));
+  fo->Write(&num_nodes, sizeof(int));
+  fo->Write(&num_deleted, sizeof(int));
+  fo->Write(&max_depth, sizeof(int));
+  fo->Write(&num_feature, sizeof(int));
+  fo->Write(&size_leaf_vector, sizeof(int));
+  fo->Write(reserved, sizeof(int) * 31);
+
+  // Write 2 nodes
+  EXPECT_EQ(sizeof(RegTree::Node),
+            3 * sizeof(int) + 1 * sizeof(unsigned) + sizeof(float));
+  int parent = -1;
+  int cleft = 1;
+  int cright = -1;
+  unsigned sindex = 5;
+  float split_or_weight = 0.5;
+  fo->Write(&parent, sizeof(int));
+  fo->Write(&cleft, sizeof(int));
+  fo->Write(&cright, sizeof(int));
+  fo->Write(&sindex, sizeof(unsigned));
+  fo->Write(&split_or_weight, sizeof(float));
+  parent = 0;
+  cleft = -1;
+  cright = -1;
+  sindex = 2;
+  split_or_weight = 0.1;
+  fo->Write(&parent, sizeof(int));
+  fo->Write(&cleft, sizeof(int));
+  fo->Write(&cright, sizeof(int));
+  fo->Write(&sindex, sizeof(unsigned));
+  fo->Write(&split_or_weight, sizeof(float));
+
+  // Write 2x node stats
+  EXPECT_EQ(sizeof(RTreeNodeStat), 3 * sizeof(float) + sizeof(int));
+  bst_float loss_chg = 5.0;
+  bst_float sum_hess = 1.0;
+  bst_float base_weight = 3.0;
+  int leaf_child_cnt = 0;
+  fo->Write(&loss_chg, sizeof(float));
+  fo->Write(&sum_hess, sizeof(float));
+  fo->Write(&base_weight, sizeof(float));
+  fo->Write(&leaf_child_cnt, sizeof(int));
+
+  loss_chg = 50.0;
+  sum_hess = 10.0;
+  base_weight = 30.0;
+  leaf_child_cnt = 0;
+  fo->Write(&loss_chg, sizeof(float));
+  fo->Write(&sum_hess, sizeof(float));
+  fo->Write(&base_weight, sizeof(float));
+  fo->Write(&leaf_child_cnt, sizeof(int));
+  fo.reset();
+  std::unique_ptr<dmlc::Stream> fi(dmlc::Stream::Create(tmp_file.c_str(), "r"));
+
+  xgboost::RegTree tree;
+  tree.Load(fi.get());
+  EXPECT_EQ(tree.GetDepth(1), 1);
+  EXPECT_EQ(tree[0].SplitCond(), 0.5f);
+  EXPECT_EQ(tree[0].SplitIndex(), 5);
+  EXPECT_EQ(tree[1].LeafValue(), 0.1f);
+  EXPECT_TRUE(tree[1].IsLeaf());
+}
+}  // namespace xgboost