[core] Add essential unit tests for TBtree

core/cont/test/CMakeLists.txt

@@ -11,3 +11,4 @@ ROOT_ADD_GTEST(TSeqTests TSeqTests.cxx LIBRARIES Core)
 ROOT_ADD_GTEST(testIter testIter.cxx LIBRARIES Core)
 ROOT_ADD_GTEST(TListTest TListTest.cxx LIBRARIES Core)
 ROOT_ADD_GTEST(THashListTest THashListTest.cxx LIBRARIES Core)
+ROOT_ADD_GTEST(TBtreeTest TBtreeTest.cxx LIBRARIES Core)

core/cont/test/TBtreeTest.cxx

@@ -0,0 +1,327 @@
+#include "gtest/gtest.h"
+#include "TBtree.h"
+#include "TNamed.h"
+#include "TObjString.h"
+
+#include <ROOT/TestSupport.hxx>
+
+#include <string>
+#include <vector>
+
+TEST(TBtreeTest, DefaultConstructor)
+{
+   TBtree tree;
+   EXPECT_EQ(0, tree.GetSize());
+   EXPECT_TRUE(tree.IsEmpty());
+   EXPECT_FALSE(tree.IsOwner());
+   EXPECT_EQ(3, tree.Order());
+}
+
+TEST(TBtreeTest, CustomOrder)
+{
+   TBtree tree(5);
+   EXPECT_EQ(0, tree.GetSize());
+   EXPECT_TRUE(tree.IsEmpty());
+   EXPECT_EQ(5, tree.Order());
+
+   // Minimum order is 3; initializing with order < 3 issues a warning and clamps to 3
+   {
+      ROOT::TestSupport::CheckDiagsRAII diags;
+      diags.requiredDiag(kWarning, "Init", "order must be at least 3", /*matchFullMessage=*/false);
+      TBtree treeSmall(2);
+      EXPECT_EQ(3, treeSmall.Order());
+   }
+}
+
+TEST(TBtreeTest, SortedInsertionAndLookup)
+{
+   TBtree tree;
+   TNamed n3("gamma", "3");
+   TNamed n1("alpha", "1");
+   TNamed n4("delta", "4");
+   TNamed n2("beta", "2");
+
+   tree.Add(&n3);
+   tree.Add(&n1);
+   tree.Add(&n4);
+   tree.Add(&n2);
+
+   EXPECT_EQ(4, tree.GetSize());
+   EXPECT_FALSE(tree.IsEmpty());
+
+   // Elements should be maintained in sorted order
+   EXPECT_EQ(&n1, tree.First());
+   EXPECT_EQ(&n1, tree.At(0));
+   EXPECT_EQ(&n1, tree[0]);
+
+   EXPECT_EQ(&n2, tree.At(1));
+   EXPECT_EQ(&n2, tree[1]);
+
+   EXPECT_EQ(&n4, tree.At(2));
+   EXPECT_EQ(&n4, tree[2]);
+
+   EXPECT_EQ(&n3, tree.Last());
+   EXPECT_EQ(&n3, tree.At(3));
+   EXPECT_EQ(&n3, tree[3]);
+
+   // Lookup by object pointer
+   EXPECT_EQ(&n2, tree.FindObject(&n2));
+
+   // Lookup by name
+   EXPECT_EQ(&n4, tree.FindObject("delta"));
+
+   // Lookup non-existent
+   TNamed notFound("epsilon", "5");
+   EXPECT_EQ(nullptr, tree.FindObject(&notFound));
+   EXPECT_EQ(nullptr, tree.FindObject("not_in_tree"));
+}
+
+TEST(TBtreeTest, Rank)
+{
+   TBtree tree;
+   TNamed n3("gamma", "3");
+   TNamed n1("alpha", "1");
+   TNamed n2("beta", "2");
+
+   tree.Add(&n3);
+   tree.Add(&n1);
+   tree.Add(&n2);
+
+   EXPECT_EQ(3, tree.GetSize());
+   EXPECT_EQ(0, tree.Rank(&n1));
+   EXPECT_EQ(1, tree.Rank(&n2));
+   EXPECT_EQ(2, tree.Rank(&n3));
+
+   TNamed notFound("omega", "99");
+   EXPECT_EQ(-1, tree.Rank(&notFound));
+}
+
+TEST(TBtreeTest, NodeSplittingAndLargeInsertion)
+{
+   // Order 3 means leaf max index is 2*(3+1)-1 = 7.
+   // Inserting 50 elements forces multiple leaf and inner node splits.
+   TBtree tree(3);
+   const int n = 50;
+   std::vector<TNamed> items;
+   items.reserve(n);
+
+   // Insert in reverse order to exercise balancing/splitting
+   for (int i = n - 1; i >= 0; --i) {
+      char key[16];
+      std::snprintf(key, sizeof(key), "key_%03d", i);
+      items.emplace_back(key, "val");
+   }
+
+   for (auto &item : items) {
+      tree.Add(&item);
+   }
+
+   EXPECT_EQ(n, tree.GetSize());
+
+   // Verify elements are strictly sorted
+   for (int i = 0; i < n; ++i) {
+      char expectedKey[16];
+      std::snprintf(expectedKey, sizeof(expectedKey), "key_%03d", i);
+      TObject *obj = tree.At(i);
+      ASSERT_NE(nullptr, obj);
+      EXPECT_STREQ(expectedKey, obj->GetName());
+      EXPECT_EQ(i, tree.Rank(obj));
+   }
+
+   // Remove every second element
+   for (int i = 0; i < n; i += 2) {
+      char expectedKey[16];
+      std::snprintf(expectedKey, sizeof(expectedKey), "key_%03d", i);
+      TNamed target(expectedKey, "val");
+      TObject *removed = tree.Remove(&target);
+      EXPECT_NE(nullptr, removed);
+      EXPECT_STREQ(expectedKey, removed->GetName());
+   }
+
+   EXPECT_EQ(n / 2, tree.GetSize());
+
+   // Verify remaining elements are still strictly sorted
+   for (int i = 0; i < n / 2; ++i) {
+      int expectedIndex = 2 * i + 1;
+      char expectedKey[16];
+      std::snprintf(expectedKey, sizeof(expectedKey), "key_%03d", expectedIndex);
+      TObject *obj = tree.At(i);
+      ASSERT_NE(nullptr, obj);
+      EXPECT_STREQ(expectedKey, obj->GetName());
+   }
+}
+
+TEST(TBtreeTest, RemoveAndClear)
+{
+   TBtree tree;
+   TNamed a("A", "1");
+   TNamed b("B", "2");
+   TNamed c("C", "3");
+
+   tree.Add(&a);
+   tree.Add(&b);
+   tree.Add(&c);
+   EXPECT_EQ(3, tree.GetSize());
+
+   // Remove middle element
+   EXPECT_EQ(&b, tree.Remove(&b));
+   EXPECT_EQ(2, tree.GetSize());
+   EXPECT_EQ(nullptr, tree.FindObject(&b));
+   EXPECT_EQ(&a, tree.At(0));
+   EXPECT_EQ(&c, tree.At(1));
+
+   // Remove non-existent object
+   TNamed notInTree("X", "9");
+   EXPECT_EQ(nullptr, tree.Remove(&notInTree));
+   EXPECT_EQ(2, tree.GetSize());
+
+   // Clear leaves objects intact
+   tree.Clear();
+   EXPECT_EQ(0, tree.GetSize());
+   EXPECT_TRUE(tree.IsEmpty());
+}
+
+namespace {
+class TrackedObj : public TNamed {
+public:
+   static int sAliveCount;
+   TrackedObj(const char *name) : TNamed(name, "") { ++sAliveCount; }
+   ~TrackedObj() override { --sAliveCount; }
+};
+int TrackedObj::sAliveCount = 0;
+} // namespace
+
+TEST(TBtreeTest, OwnershipAndClearDelete)
+{
+   TrackedObj::sAliveCount = 0;
+
+   // Non-owning tree: Clear does not destroy objects
+   {
+      TBtree tree;
+      auto *obj1 = new TrackedObj("obj1");
+      auto *obj2 = new TrackedObj("obj2");
+      tree.Add(obj1);
+      tree.Add(obj2);
+      EXPECT_EQ(2, TrackedObj::sAliveCount);
+
+      tree.Clear();
+      EXPECT_EQ(0, tree.GetSize());
+      EXPECT_EQ(2, TrackedObj::sAliveCount);
+
+      tree.Add(obj1);
+      tree.Add(obj2);
+      tree.Delete();
+      EXPECT_EQ(0, tree.GetSize());
+      EXPECT_EQ(0, TrackedObj::sAliveCount);
+   }
+
+   // Owning tree: Clear destroys owned objects
+   TrackedObj::sAliveCount = 0;
+   {
+      TBtree tree;
+      tree.SetOwner(kTRUE);
+      EXPECT_TRUE(tree.IsOwner());
+
+      tree.Add(new TrackedObj("obj1"));
+      tree.Add(new TrackedObj("obj2"));
+      EXPECT_EQ(2, TrackedObj::sAliveCount);
+
+      tree.Clear();
+      EXPECT_EQ(0, tree.GetSize());
+      EXPECT_EQ(0, TrackedObj::sAliveCount);
+
+      tree.Add(new TrackedObj("obj3"));
+      tree.Add(new TrackedObj("obj4"));
+      EXPECT_EQ(2, TrackedObj::sAliveCount);
+   }
+   // Destructor cleans up owned objects
+   EXPECT_EQ(0, TrackedObj::sAliveCount);
+}
+
+TEST(TBtreeTest, Iteration)
+{
+   TBtree tree;
+   TNamed a("A", "1");
+   TNamed b("B", "2");
+   TNamed c("C", "3");
+
+   tree.Add(&c);
+   tree.Add(&a);
+   tree.Add(&b);
+
+   // Forward iteration
+   {
+      TIter next(&tree);
+      EXPECT_EQ(&a, next());
+      EXPECT_EQ(&b, next());
+      EXPECT_EQ(&c, next());
+      EXPECT_EQ(nullptr, next());
+
+      next.Reset();
+      EXPECT_EQ(&a, next());
+   }
+
+   // Backward iteration
+   {
+      TIter next(&tree, kIterBackward);
+      EXPECT_EQ(&c, next());
+      EXPECT_EQ(&b, next());
+      EXPECT_EQ(&a, next());
+      EXPECT_EQ(nullptr, next());
+   }
+
+   // TBtreeIter direct usage
+   {
+      TBtreeIter iter(&tree);
+      EXPECT_EQ(&tree, iter.GetCollection());
+      EXPECT_EQ(&a, iter.Next());
+      EXPECT_EQ(&a, *iter);
+      EXPECT_EQ(&b, iter.Next());
+      EXPECT_EQ(&b, *iter);
+      EXPECT_EQ(&c, iter.Next());
+      EXPECT_EQ(&c, *iter);
+      EXPECT_EQ(nullptr, iter.Next());
+   }
+}
+
+TEST(TBtreeTest, ErrorDiagnosticsForNonSortable)
+{
+   TBtree tree;
+   TObject nonSortable; // TObject::IsSortable() returns kFALSE
+
+   {
+      ROOT::TestSupport::CheckDiagsRAII diags;
+      diags.requiredDiag(kError, "Add", "object must be sortable", /*matchFullMessage=*/false);
+      tree.Add(&nonSortable);
+   }
+
+   {
+      ROOT::TestSupport::CheckDiagsRAII diags;
+      diags.requiredDiag(kError, "FindObject", "object must be sortable", /*matchFullMessage=*/false);
+      EXPECT_EQ(nullptr, tree.FindObject(&nonSortable));
+   }
+
+   {
+      ROOT::TestSupport::CheckDiagsRAII diags;
+      diags.requiredDiag(kError, "Rank", "object must be sortable", /*matchFullMessage=*/false);
+      EXPECT_EQ(-1, tree.Rank(&nonSortable));
+   }
+
+   {
+      ROOT::TestSupport::CheckDiagsRAII diags;
+      diags.requiredDiag(kError, "Remove", "object must be sortable", /*matchFullMessage=*/false);
+      EXPECT_EQ(nullptr, tree.Remove(&nonSortable));
+   }
+
+   // Before and After are forbidden because Btree controls sorting order
+   {
+      ROOT::TestSupport::CheckDiagsRAII diags;
+      diags.requiredDiag(kError, "TBtree::Before", "May not use this method", /*matchFullMessage=*/false);
+      EXPECT_EQ(nullptr, tree.Before(&nonSortable));
+   }
+   {
+      ROOT::TestSupport::CheckDiagsRAII diags;
+      diags.requiredDiag(kError, "TBtree::After", "Cannot use this method", /*matchFullMessage=*/false);
+      EXPECT_EQ(nullptr, tree.After(&nonSortable));
+   }
+}