Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1408 insertions, 0 deletions

diff --git a/gfx/tests/gtest/TestTreeTraversal.cpp b/gfx/tests/gtest/TestTreeTraversal.cpp
new file mode 100644
index 0000000000..7e538ca514
--- /dev/null
+++ b/gfx/tests/gtest/TestTreeTraversal.cpp
@@ -0,0 +1,1408 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <vector>
+#include "mozilla/RefPtr.h"
+#include "gtest/gtest.h"
+#include "nsRegion.h"
+#include "nsRect.h"
+#include "TreeTraversal.h"
+#include <stack>
+#include <queue>
+
+using namespace mozilla::layers;
+using namespace mozilla;
+
+enum class SearchNodeType { Needle, Hay };
+enum class ForEachNodeType { Continue, Skip };
+
+template <class T>
+class TestNodeBase {
+ public:
+  NS_INLINE_DECL_REFCOUNTING(TestNodeBase<T>);
+  explicit TestNodeBase(T aType, int aExpectedTraversalRank = -1);
+  explicit TestNodeBase();
+  void SetActualTraversalRank(int aRank);
+  void SetValue(int aValue);
+  void SetType(T aType);
+  void SetRegion(nsRegion aRegion);
+  int GetExpectedTraversalRank();
+  int GetActualTraversalRank();
+  int GetValue();
+  T GetType();
+  nsRegion GetRegion();
+  virtual bool IsLeaf() = 0;
+
+ private:
+  MOZ_INIT_OUTSIDE_CTOR int mExpectedTraversalRank;
+  MOZ_INIT_OUTSIDE_CTOR int mActualTraversalRank;
+  MOZ_INIT_OUTSIDE_CTOR int mValue;
+  MOZ_INIT_OUTSIDE_CTOR nsRegion mRegion;
+  MOZ_INIT_OUTSIDE_CTOR T mType;
+
+ protected:
+  virtual ~TestNodeBase() = default;
+};
+
+template <class T>
+class TestNodeReverse : public TestNodeBase<T> {
+ public:
+  explicit TestNodeReverse(T aType, int aExpectedTraversalRank = -1);
+  explicit TestNodeReverse();
+  void AddChild(RefPtr<TestNodeReverse<T>> aNode);
+  TestNodeReverse<T>* GetLastChild();
+  TestNodeReverse<T>* GetPrevSibling();
+  bool IsLeaf();
+
+ private:
+  void SetPrevSibling(RefPtr<TestNodeReverse<T>> aNode);
+  void SetLastChild(RefPtr<TestNodeReverse<T>> aNode);
+  RefPtr<TestNodeReverse<T>> mSiblingNode;
+  RefPtr<TestNodeReverse<T>> mLastChildNode;
+  ~TestNodeReverse() = default;
+};
+
+template <class T>
+class TestNodeForward : public TestNodeBase<T> {
+ public:
+  explicit TestNodeForward(T aType, int aExpectedTraversalRank = -1);
+  explicit TestNodeForward();
+  void AddChild(RefPtr<TestNodeForward<T>> aNode);
+  TestNodeForward<T>* GetFirstChild();
+  TestNodeForward<T>* GetNextSibling();
+  bool IsLeaf();
+
+ private:
+  void SetNextSibling(RefPtr<TestNodeForward<T>> aNode);
+  void SetLastChild(RefPtr<TestNodeForward<T>> aNode);
+  void SetFirstChild(RefPtr<TestNodeForward<T>> aNode);
+  RefPtr<TestNodeForward<T>> mSiblingNode = nullptr;
+  RefPtr<TestNodeForward<T>> mFirstChildNode = nullptr;
+  // Track last child to facilitate appending children
+  RefPtr<TestNodeForward<T>> mLastChildNode = nullptr;
+  ~TestNodeForward() = default;
+};
+
+template <class T>
+TestNodeReverse<T>::TestNodeReverse(T aType, int aExpectedTraversalRank)
+    : TestNodeBase<T>(aType, aExpectedTraversalRank) {}
+
+template <class T>
+TestNodeReverse<T>::TestNodeReverse() : TestNodeBase<T>() {}
+
+template <class T>
+void TestNodeReverse<T>::SetLastChild(RefPtr<TestNodeReverse<T>> aNode) {
+  mLastChildNode = aNode;
+}
+
+template <class T>
+void TestNodeReverse<T>::AddChild(RefPtr<TestNodeReverse<T>> aNode) {
+  aNode->SetPrevSibling(mLastChildNode);
+  SetLastChild(aNode);
+}
+
+template <class T>
+void TestNodeReverse<T>::SetPrevSibling(RefPtr<TestNodeReverse<T>> aNode) {
+  mSiblingNode = aNode;
+}
+
+template <class T>
+TestNodeReverse<T>* TestNodeReverse<T>::GetLastChild() {
+  return mLastChildNode;
+}
+
+template <class T>
+TestNodeReverse<T>* TestNodeReverse<T>::GetPrevSibling() {
+  return mSiblingNode;
+}
+
+template <class T>
+bool TestNodeReverse<T>::IsLeaf() {
+  return !mLastChildNode;
+}
+
+template <class T>
+TestNodeForward<T>::TestNodeForward(T aType, int aExpectedTraversalRank)
+    : TestNodeBase<T>(aType, aExpectedTraversalRank) {}
+
+template <class T>
+TestNodeForward<T>::TestNodeForward() : TestNodeBase<T>() {}
+
+template <class T>
+void TestNodeForward<T>::AddChild(RefPtr<TestNodeForward<T>> aNode) {
+  if (mFirstChildNode == nullptr) {
+    SetFirstChild(aNode);
+    SetLastChild(aNode);
+  } else {
+    mLastChildNode->SetNextSibling(aNode);
+    SetLastChild(aNode);
+  }
+}
+
+template <class T>
+void TestNodeForward<T>::SetLastChild(RefPtr<TestNodeForward<T>> aNode) {
+  mLastChildNode = aNode;
+}
+
+template <class T>
+void TestNodeForward<T>::SetFirstChild(RefPtr<TestNodeForward<T>> aNode) {
+  mFirstChildNode = aNode;
+}
+
+template <class T>
+void TestNodeForward<T>::SetNextSibling(RefPtr<TestNodeForward<T>> aNode) {
+  mSiblingNode = aNode;
+}
+
+template <class T>
+bool TestNodeForward<T>::IsLeaf() {
+  return !mFirstChildNode;
+}
+
+template <class T>
+TestNodeForward<T>* TestNodeForward<T>::GetFirstChild() {
+  return mFirstChildNode;
+}
+
+template <class T>
+TestNodeForward<T>* TestNodeForward<T>::GetNextSibling() {
+  return mSiblingNode;
+}
+
+template <class T>
+TestNodeBase<T>::TestNodeBase(T aType, int aExpectedTraversalRank)
+    : mExpectedTraversalRank(aExpectedTraversalRank),
+      mActualTraversalRank(-1),
+      mType(aType) {}
+
+template <class T>
+TestNodeBase<T>::TestNodeBase() = default;
+
+template <class T>
+int TestNodeBase<T>::GetActualTraversalRank() {
+  return mActualTraversalRank;
+}
+
+template <class T>
+void TestNodeBase<T>::SetActualTraversalRank(int aRank) {
+  mActualTraversalRank = aRank;
+}
+
+template <class T>
+int TestNodeBase<T>::GetExpectedTraversalRank() {
+  return mExpectedTraversalRank;
+}
+
+template <class T>
+T TestNodeBase<T>::GetType() {
+  return mType;
+}
+
+template <class T>
+void TestNodeBase<T>::SetType(T aType) {
+  mType = aType;
+}
+
+template <class T>
+nsRegion TestNodeBase<T>::GetRegion() {
+  return mRegion;
+}
+
+template <class T>
+void TestNodeBase<T>::SetRegion(nsRegion aRegion) {
+  mRegion = aRegion;
+}
+
+template <class T>
+int TestNodeBase<T>::GetValue() {
+  return mValue;
+}
+
+template <class T>
+void TestNodeBase<T>::SetValue(int aValue) {
+  mValue = aValue;
+}
+
+typedef TestNodeBase<SearchNodeType> SearchTestNode;
+typedef TestNodeBase<ForEachNodeType> ForEachTestNode;
+typedef TestNodeReverse<SearchNodeType> SearchTestNodeReverse;
+typedef TestNodeReverse<ForEachNodeType> ForEachTestNodeReverse;
+typedef TestNodeForward<SearchNodeType> SearchTestNodeForward;
+typedef TestNodeForward<ForEachNodeType> ForEachTestNodeForward;
+
+TEST(TreeTraversal, DepthFirstSearchNull)
+{
+  RefPtr<SearchTestNodeReverse> nullNode;
+  RefPtr<SearchTestNodeReverse> result =
+      DepthFirstSearch<layers::ReverseIterator>(
+          nullNode.get(), [](SearchTestNodeReverse* aNode) {
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+  ASSERT_EQ(result.get(), nullptr)
+      << "Null root did not return null search result.";
+}
+
+TEST(TreeTraversal, DepthFirstSearchValueExists)
+{
+  int visitCount = 0;
+  size_t expectedNeedleTraversalRank = 7;
+  RefPtr<SearchTestNodeForward> needleNode;
+  std::vector<RefPtr<SearchTestNodeForward>> nodeList;
+  nodeList.reserve(10);
+  for (size_t i = 0; i < 10; i++) {
+    if (i == expectedNeedleTraversalRank) {
+      needleNode = new SearchTestNodeForward(SearchNodeType::Needle, i);
+      nodeList.push_back(needleNode);
+    } else if (i < expectedNeedleTraversalRank) {
+      nodeList.push_back(new SearchTestNodeForward(SearchNodeType::Hay, i));
+    } else {
+      nodeList.push_back(new SearchTestNodeForward(SearchNodeType::Hay));
+    }
+  }
+
+  RefPtr<SearchTestNodeForward> root = nodeList[0];
+  nodeList[0]->AddChild(nodeList[1]);
+  nodeList[0]->AddChild(nodeList[4]);
+  nodeList[1]->AddChild(nodeList[2]);
+  nodeList[1]->AddChild(nodeList[3]);
+  nodeList[4]->AddChild(nodeList[5]);
+  nodeList[4]->AddChild(nodeList[6]);
+  nodeList[6]->AddChild(nodeList[7]);
+  nodeList[7]->AddChild(nodeList[8]);
+  nodeList[7]->AddChild(nodeList[9]);
+
+  RefPtr<SearchTestNodeForward> foundNode =
+      DepthFirstSearch<layers::ForwardIterator>(
+          root.get(), [&visitCount](SearchTestNodeForward* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+
+  for (size_t i = 0; i < nodeList.size(); i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  ASSERT_EQ(foundNode, needleNode) << "Search did not return expected node.";
+  ASSERT_EQ(foundNode->GetType(), SearchNodeType::Needle)
+      << "Returned node does not match expected value (something odd "
+         "happened).";
+}
+
+TEST(TreeTraversal, DepthFirstSearchValueExistsReverse)
+{
+  int visitCount = 0;
+  size_t expectedNeedleTraversalRank = 7;
+  RefPtr<SearchTestNodeReverse> needleNode;
+  std::vector<RefPtr<SearchTestNodeReverse>> nodeList;
+  nodeList.reserve(10);
+  for (size_t i = 0; i < 10; i++) {
+    if (i == expectedNeedleTraversalRank) {
+      needleNode = new SearchTestNodeReverse(SearchNodeType::Needle, i);
+      nodeList.push_back(needleNode);
+    } else if (i < expectedNeedleTraversalRank) {
+      nodeList.push_back(new SearchTestNodeReverse(SearchNodeType::Hay, i));
+    } else {
+      nodeList.push_back(new SearchTestNodeReverse(SearchNodeType::Hay));
+    }
+  }
+
+  RefPtr<SearchTestNodeReverse> root = nodeList[0];
+  nodeList[0]->AddChild(nodeList[4]);
+  nodeList[0]->AddChild(nodeList[1]);
+  nodeList[1]->AddChild(nodeList[3]);
+  nodeList[1]->AddChild(nodeList[2]);
+  nodeList[4]->AddChild(nodeList[6]);
+  nodeList[4]->AddChild(nodeList[5]);
+  nodeList[6]->AddChild(nodeList[7]);
+  nodeList[7]->AddChild(nodeList[9]);
+  nodeList[7]->AddChild(nodeList[8]);
+
+  RefPtr<SearchTestNodeReverse> foundNode =
+      DepthFirstSearch<layers::ReverseIterator>(
+          root.get(), [&visitCount](SearchTestNodeReverse* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+
+  for (size_t i = 0; i < nodeList.size(); i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  ASSERT_EQ(foundNode, needleNode) << "Search did not return expected node.";
+  ASSERT_EQ(foundNode->GetType(), SearchNodeType::Needle)
+      << "Returned node does not match expected value (something odd "
+         "happened).";
+}
+
+TEST(TreeTraversal, DepthFirstSearchRootIsNeedle)
+{
+  RefPtr<SearchTestNodeReverse> root =
+      new SearchTestNodeReverse(SearchNodeType::Needle, 0);
+  RefPtr<SearchTestNodeReverse> childNode1 =
+      new SearchTestNodeReverse(SearchNodeType::Hay);
+  RefPtr<SearchTestNodeReverse> childNode2 =
+      new SearchTestNodeReverse(SearchNodeType::Hay);
+  int visitCount = 0;
+  RefPtr<SearchTestNodeReverse> result =
+      DepthFirstSearch<layers::ReverseIterator>(
+          root.get(), [&visitCount](SearchTestNodeReverse* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+  ASSERT_EQ(result, root) << "Search starting at needle did not return needle.";
+  ASSERT_EQ(root->GetExpectedTraversalRank(), root->GetActualTraversalRank())
+      << "Search starting at needle did not return needle.";
+  ASSERT_EQ(childNode1->GetExpectedTraversalRank(),
+            childNode1->GetActualTraversalRank())
+      << "Search starting at needle continued past needle.";
+  ASSERT_EQ(childNode2->GetExpectedTraversalRank(),
+            childNode2->GetActualTraversalRank())
+      << "Search starting at needle continued past needle.";
+}
+
+TEST(TreeTraversal, DepthFirstSearchValueDoesNotExist)
+{
+  int visitCount = 0;
+  std::vector<RefPtr<SearchTestNodeForward>> nodeList;
+  nodeList.reserve(10);
+  for (int i = 0; i < 10; i++) {
+    nodeList.push_back(new SearchTestNodeForward(SearchNodeType::Hay, i));
+  }
+
+  RefPtr<SearchTestNodeForward> root = nodeList[0];
+  nodeList[0]->AddChild(nodeList[1]);
+  nodeList[0]->AddChild(nodeList[4]);
+  nodeList[1]->AddChild(nodeList[2]);
+  nodeList[1]->AddChild(nodeList[3]);
+  nodeList[4]->AddChild(nodeList[5]);
+  nodeList[4]->AddChild(nodeList[6]);
+  nodeList[6]->AddChild(nodeList[7]);
+  nodeList[7]->AddChild(nodeList[8]);
+  nodeList[7]->AddChild(nodeList[9]);
+
+  RefPtr<SearchTestNodeForward> foundNode =
+      DepthFirstSearch<layers::ForwardIterator>(
+          root.get(), [&visitCount](SearchTestNodeForward* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+
+  for (int i = 0; i < 10; i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  ASSERT_EQ(foundNode.get(), nullptr)
+      << "Search found something that should not exist.";
+}
+
+TEST(TreeTraversal, DepthFirstSearchValueDoesNotExistReverse)
+{
+  int visitCount = 0;
+  std::vector<RefPtr<SearchTestNodeReverse>> nodeList;
+  nodeList.reserve(10);
+  for (int i = 0; i < 10; i++) {
+    nodeList.push_back(new SearchTestNodeReverse(SearchNodeType::Hay, i));
+  }
+
+  RefPtr<SearchTestNodeReverse> root = nodeList[0];
+  nodeList[0]->AddChild(nodeList[4]);
+  nodeList[0]->AddChild(nodeList[1]);
+  nodeList[1]->AddChild(nodeList[3]);
+  nodeList[1]->AddChild(nodeList[2]);
+  nodeList[4]->AddChild(nodeList[6]);
+  nodeList[4]->AddChild(nodeList[5]);
+  nodeList[6]->AddChild(nodeList[7]);
+  nodeList[7]->AddChild(nodeList[9]);
+  nodeList[7]->AddChild(nodeList[8]);
+
+  RefPtr<SearchTestNodeReverse> foundNode =
+      DepthFirstSearch<layers::ReverseIterator>(
+          root.get(), [&visitCount](SearchTestNodeReverse* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+
+  for (int i = 0; i < 10; i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  ASSERT_EQ(foundNode.get(), nullptr)
+      << "Search found something that should not exist.";
+}
+
+TEST(TreeTraversal, DepthFirstSearchPostOrderNull)
+{
+  RefPtr<SearchTestNodeReverse> nullNode;
+  RefPtr<SearchTestNodeReverse> result =
+      DepthFirstSearchPostOrder<layers::ReverseIterator>(
+          nullNode.get(), [](SearchTestNodeReverse* aNode) {
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+  ASSERT_EQ(result.get(), nullptr)
+      << "Null root did not return null search result.";
+}
+
+TEST(TreeTraversal, DepthFirstSearchPostOrderValueExists)
+{
+  int visitCount = 0;
+  size_t expectedNeedleTraversalRank = 7;
+  RefPtr<SearchTestNodeForward> needleNode;
+  std::vector<RefPtr<SearchTestNodeForward>> nodeList;
+  for (size_t i = 0; i < 10; i++) {
+    if (i == expectedNeedleTraversalRank) {
+      needleNode = new SearchTestNodeForward(SearchNodeType::Needle, i);
+      nodeList.push_back(needleNode);
+    } else if (i < expectedNeedleTraversalRank) {
+      nodeList.push_back(new SearchTestNodeForward(SearchNodeType::Hay, i));
+    } else {
+      nodeList.push_back(new SearchTestNodeForward(SearchNodeType::Hay));
+    }
+  }
+
+  RefPtr<SearchTestNodeForward> root = nodeList[9];
+  nodeList[9]->AddChild(nodeList[2]);
+  nodeList[9]->AddChild(nodeList[8]);
+  nodeList[2]->AddChild(nodeList[0]);
+  nodeList[2]->AddChild(nodeList[1]);
+  nodeList[8]->AddChild(nodeList[6]);
+  nodeList[8]->AddChild(nodeList[7]);
+  nodeList[6]->AddChild(nodeList[5]);
+  nodeList[5]->AddChild(nodeList[3]);
+  nodeList[5]->AddChild(nodeList[4]);
+
+  RefPtr<SearchTestNodeForward> foundNode =
+      DepthFirstSearchPostOrder<layers::ForwardIterator>(
+          root.get(), [&visitCount](SearchTestNodeForward* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+
+  for (size_t i = 0; i < nodeList.size(); i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  ASSERT_EQ(foundNode, needleNode) << "Search did not return expected node.";
+  ASSERT_EQ(foundNode->GetType(), SearchNodeType::Needle)
+      << "Returned node does not match expected value (something odd "
+         "happened).";
+}
+
+TEST(TreeTraversal, DepthFirstSearchPostOrderValueExistsReverse)
+{
+  int visitCount = 0;
+  size_t expectedNeedleTraversalRank = 7;
+  RefPtr<SearchTestNodeReverse> needleNode;
+  std::vector<RefPtr<SearchTestNodeReverse>> nodeList;
+  for (size_t i = 0; i < 10; i++) {
+    if (i == expectedNeedleTraversalRank) {
+      needleNode = new SearchTestNodeReverse(SearchNodeType::Needle, i);
+      nodeList.push_back(needleNode);
+    } else if (i < expectedNeedleTraversalRank) {
+      nodeList.push_back(new SearchTestNodeReverse(SearchNodeType::Hay, i));
+    } else {
+      nodeList.push_back(new SearchTestNodeReverse(SearchNodeType::Hay));
+    }
+  }
+
+  RefPtr<SearchTestNodeReverse> root = nodeList[9];
+  nodeList[9]->AddChild(nodeList[8]);
+  nodeList[9]->AddChild(nodeList[2]);
+  nodeList[2]->AddChild(nodeList[1]);
+  nodeList[2]->AddChild(nodeList[0]);
+  nodeList[8]->AddChild(nodeList[7]);
+  nodeList[8]->AddChild(nodeList[6]);
+  nodeList[6]->AddChild(nodeList[5]);
+  nodeList[5]->AddChild(nodeList[4]);
+  nodeList[5]->AddChild(nodeList[3]);
+
+  RefPtr<SearchTestNodeReverse> foundNode =
+      DepthFirstSearchPostOrder<layers::ReverseIterator>(
+          root.get(), [&visitCount](SearchTestNodeReverse* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+
+  for (size_t i = 0; i < nodeList.size(); i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  ASSERT_EQ(foundNode, needleNode) << "Search did not return expected node.";
+  ASSERT_EQ(foundNode->GetType(), SearchNodeType::Needle)
+      << "Returned node does not match expected value (something odd "
+         "happened).";
+}
+
+TEST(TreeTraversal, DepthFirstSearchPostOrderRootIsNeedle)
+{
+  RefPtr<SearchTestNodeReverse> root =
+      new SearchTestNodeReverse(SearchNodeType::Needle, 0);
+  RefPtr<SearchTestNodeReverse> childNode1 =
+      new SearchTestNodeReverse(SearchNodeType::Hay);
+  RefPtr<SearchTestNodeReverse> childNode2 =
+      new SearchTestNodeReverse(SearchNodeType::Hay);
+  int visitCount = 0;
+  RefPtr<SearchTestNodeReverse> result =
+      DepthFirstSearchPostOrder<layers::ReverseIterator>(
+          root.get(), [&visitCount](SearchTestNodeReverse* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+  ASSERT_EQ(result, root) << "Search starting at needle did not return needle.";
+  ASSERT_EQ(root->GetExpectedTraversalRank(), root->GetActualTraversalRank())
+      << "Search starting at needle did not return needle.";
+  ASSERT_EQ(childNode1->GetExpectedTraversalRank(),
+            childNode1->GetActualTraversalRank())
+      << "Search starting at needle continued past needle.";
+  ASSERT_EQ(childNode2->GetExpectedTraversalRank(),
+            childNode2->GetActualTraversalRank())
+      << "Search starting at needle continued past needle.";
+}
+
+TEST(TreeTraversal, DepthFirstSearchPostOrderValueDoesNotExist)
+{
+  int visitCount = 0;
+  std::vector<RefPtr<SearchTestNodeForward>> nodeList;
+  nodeList.reserve(10);
+  for (int i = 0; i < 10; i++) {
+    nodeList.push_back(new SearchTestNodeForward(SearchNodeType::Hay, i));
+  }
+
+  RefPtr<SearchTestNodeForward> root = nodeList[9];
+  nodeList[9]->AddChild(nodeList[2]);
+  nodeList[9]->AddChild(nodeList[8]);
+  nodeList[2]->AddChild(nodeList[0]);
+  nodeList[2]->AddChild(nodeList[1]);
+  nodeList[8]->AddChild(nodeList[6]);
+  nodeList[8]->AddChild(nodeList[7]);
+  nodeList[6]->AddChild(nodeList[5]);
+  nodeList[5]->AddChild(nodeList[3]);
+  nodeList[5]->AddChild(nodeList[4]);
+
+  RefPtr<SearchTestNodeForward> foundNode =
+      DepthFirstSearchPostOrder<layers::ForwardIterator>(
+          root.get(), [&visitCount](SearchTestNodeForward* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+
+  for (int i = 0; i < 10; i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  ASSERT_EQ(foundNode.get(), nullptr)
+      << "Search found something that should not exist.";
+}
+
+TEST(TreeTraversal, DepthFirstSearchPostOrderValueDoesNotExistReverse)
+{
+  int visitCount = 0;
+  std::vector<RefPtr<SearchTestNodeReverse>> nodeList;
+  nodeList.reserve(10);
+  for (int i = 0; i < 10; i++) {
+    nodeList.push_back(new SearchTestNodeReverse(SearchNodeType::Hay, i));
+  }
+
+  RefPtr<SearchTestNodeReverse> root = nodeList[9];
+  nodeList[9]->AddChild(nodeList[8]);
+  nodeList[9]->AddChild(nodeList[2]);
+  nodeList[2]->AddChild(nodeList[1]);
+  nodeList[2]->AddChild(nodeList[0]);
+  nodeList[8]->AddChild(nodeList[7]);
+  nodeList[8]->AddChild(nodeList[6]);
+  nodeList[6]->AddChild(nodeList[5]);
+  nodeList[5]->AddChild(nodeList[4]);
+  nodeList[5]->AddChild(nodeList[3]);
+
+  RefPtr<SearchTestNodeReverse> foundNode =
+      DepthFirstSearchPostOrder<layers::ReverseIterator>(
+          root.get(), [&visitCount](SearchTestNodeReverse* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+
+  for (int i = 0; i < 10; i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  ASSERT_EQ(foundNode.get(), nullptr)
+      << "Search found something that should not exist.";
+}
+
+TEST(TreeTraversal, BreadthFirstSearchNull)
+{
+  RefPtr<SearchTestNodeReverse> nullNode;
+  RefPtr<SearchTestNodeReverse> result =
+      BreadthFirstSearch<layers::ReverseIterator>(
+          nullNode.get(), [](SearchTestNodeReverse* aNode) {
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+  ASSERT_EQ(result.get(), nullptr)
+      << "Null root did not return null search result.";
+}
+
+TEST(TreeTraversal, BreadthFirstSearchRootIsNeedle)
+{
+  RefPtr<SearchTestNodeReverse> root =
+      new SearchTestNodeReverse(SearchNodeType::Needle, 0);
+  RefPtr<SearchTestNodeReverse> childNode1 =
+      new SearchTestNodeReverse(SearchNodeType::Hay);
+  RefPtr<SearchTestNodeReverse> childNode2 =
+      new SearchTestNodeReverse(SearchNodeType::Hay);
+  int visitCount = 0;
+  RefPtr<SearchTestNodeReverse> result =
+      BreadthFirstSearch<layers::ReverseIterator>(
+          root.get(), [&visitCount](SearchTestNodeReverse* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+  ASSERT_EQ(result, root) << "Search starting at needle did not return needle.";
+  ASSERT_EQ(root->GetExpectedTraversalRank(), root->GetActualTraversalRank())
+      << "Search starting at needle did not return needle.";
+  ASSERT_EQ(childNode1->GetExpectedTraversalRank(),
+            childNode1->GetActualTraversalRank())
+      << "Search starting at needle continued past needle.";
+  ASSERT_EQ(childNode2->GetExpectedTraversalRank(),
+            childNode2->GetActualTraversalRank())
+      << "Search starting at needle continued past needle.";
+}
+
+TEST(TreeTraversal, BreadthFirstSearchValueExists)
+{
+  int visitCount = 0;
+  size_t expectedNeedleTraversalRank = 7;
+  RefPtr<SearchTestNodeForward> needleNode;
+  std::vector<RefPtr<SearchTestNodeForward>> nodeList;
+  nodeList.reserve(10);
+  for (size_t i = 0; i < 10; i++) {
+    if (i == expectedNeedleTraversalRank) {
+      needleNode = new SearchTestNodeForward(SearchNodeType::Needle, i);
+      nodeList.push_back(needleNode);
+    } else if (i < expectedNeedleTraversalRank) {
+      nodeList.push_back(new SearchTestNodeForward(SearchNodeType::Hay, i));
+    } else {
+      nodeList.push_back(new SearchTestNodeForward(SearchNodeType::Hay));
+    }
+  }
+
+  RefPtr<SearchTestNodeForward> root = nodeList[0];
+  nodeList[0]->AddChild(nodeList[1]);
+  nodeList[0]->AddChild(nodeList[2]);
+  nodeList[1]->AddChild(nodeList[3]);
+  nodeList[1]->AddChild(nodeList[4]);
+  nodeList[2]->AddChild(nodeList[5]);
+  nodeList[2]->AddChild(nodeList[6]);
+  nodeList[6]->AddChild(nodeList[7]);
+  nodeList[7]->AddChild(nodeList[8]);
+  nodeList[7]->AddChild(nodeList[9]);
+
+  RefPtr<SearchTestNodeForward> foundNode =
+      BreadthFirstSearch<layers::ForwardIterator>(
+          root.get(), [&visitCount](SearchTestNodeForward* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+
+  for (size_t i = 0; i < nodeList.size(); i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  ASSERT_EQ(foundNode, needleNode) << "Search did not return expected node.";
+  ASSERT_EQ(foundNode->GetType(), SearchNodeType::Needle)
+      << "Returned node does not match expected value (something odd "
+         "happened).";
+}
+
+TEST(TreeTraversal, BreadthFirstSearchValueExistsReverse)
+{
+  int visitCount = 0;
+  size_t expectedNeedleTraversalRank = 7;
+  RefPtr<SearchTestNodeReverse> needleNode;
+  std::vector<RefPtr<SearchTestNodeReverse>> nodeList;
+  nodeList.reserve(10);
+  for (size_t i = 0; i < 10; i++) {
+    if (i == expectedNeedleTraversalRank) {
+      needleNode = new SearchTestNodeReverse(SearchNodeType::Needle, i);
+      nodeList.push_back(needleNode);
+    } else if (i < expectedNeedleTraversalRank) {
+      nodeList.push_back(new SearchTestNodeReverse(SearchNodeType::Hay, i));
+    } else {
+      nodeList.push_back(new SearchTestNodeReverse(SearchNodeType::Hay));
+    }
+  }
+
+  RefPtr<SearchTestNodeReverse> root = nodeList[0];
+  nodeList[0]->AddChild(nodeList[2]);
+  nodeList[0]->AddChild(nodeList[1]);
+  nodeList[1]->AddChild(nodeList[4]);
+  nodeList[1]->AddChild(nodeList[3]);
+  nodeList[2]->AddChild(nodeList[6]);
+  nodeList[2]->AddChild(nodeList[5]);
+  nodeList[6]->AddChild(nodeList[7]);
+  nodeList[7]->AddChild(nodeList[9]);
+  nodeList[7]->AddChild(nodeList[8]);
+
+  RefPtr<SearchTestNodeReverse> foundNode =
+      BreadthFirstSearch<layers::ReverseIterator>(
+          root.get(), [&visitCount](SearchTestNodeReverse* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+
+  for (size_t i = 0; i < nodeList.size(); i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  ASSERT_EQ(foundNode, needleNode) << "Search did not return expected node.";
+  ASSERT_EQ(foundNode->GetType(), SearchNodeType::Needle)
+      << "Returned node does not match expected value (something odd "
+         "happened).";
+}
+
+TEST(TreeTraversal, BreadthFirstSearchValueDoesNotExist)
+{
+  int visitCount = 0;
+  std::vector<RefPtr<SearchTestNodeForward>> nodeList;
+  nodeList.reserve(10);
+  for (int i = 0; i < 10; i++) {
+    nodeList.push_back(new SearchTestNodeForward(SearchNodeType::Hay, i));
+  }
+
+  RefPtr<SearchTestNodeForward> root = nodeList[0];
+  nodeList[0]->AddChild(nodeList[1]);
+  nodeList[0]->AddChild(nodeList[2]);
+  nodeList[1]->AddChild(nodeList[3]);
+  nodeList[1]->AddChild(nodeList[4]);
+  nodeList[2]->AddChild(nodeList[5]);
+  nodeList[2]->AddChild(nodeList[6]);
+  nodeList[6]->AddChild(nodeList[7]);
+  nodeList[7]->AddChild(nodeList[8]);
+  nodeList[7]->AddChild(nodeList[9]);
+
+  RefPtr<SearchTestNodeForward> foundNode =
+      BreadthFirstSearch<layers::ForwardIterator>(
+          root.get(), [&visitCount](SearchTestNodeForward* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+
+  for (size_t i = 0; i < nodeList.size(); i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  ASSERT_EQ(foundNode.get(), nullptr)
+      << "Search found something that should not exist.";
+}
+
+TEST(TreeTraversal, BreadthFirstSearchValueDoesNotExistReverse)
+{
+  int visitCount = 0;
+  std::vector<RefPtr<SearchTestNodeReverse>> nodeList;
+  nodeList.reserve(10);
+  for (int i = 0; i < 10; i++) {
+    nodeList.push_back(new SearchTestNodeReverse(SearchNodeType::Hay, i));
+  }
+
+  RefPtr<SearchTestNodeReverse> root = nodeList[0];
+  nodeList[0]->AddChild(nodeList[2]);
+  nodeList[0]->AddChild(nodeList[1]);
+  nodeList[1]->AddChild(nodeList[4]);
+  nodeList[1]->AddChild(nodeList[3]);
+  nodeList[2]->AddChild(nodeList[6]);
+  nodeList[2]->AddChild(nodeList[5]);
+  nodeList[6]->AddChild(nodeList[7]);
+  nodeList[7]->AddChild(nodeList[9]);
+  nodeList[7]->AddChild(nodeList[8]);
+
+  RefPtr<SearchTestNodeReverse> foundNode =
+      BreadthFirstSearch<layers::ReverseIterator>(
+          root.get(), [&visitCount](SearchTestNodeReverse* aNode) {
+            aNode->SetActualTraversalRank(visitCount);
+            visitCount++;
+            return aNode->GetType() == SearchNodeType::Needle;
+          });
+
+  for (size_t i = 0; i < nodeList.size(); i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  ASSERT_EQ(foundNode.get(), nullptr)
+      << "Search found something that should not exist.";
+}
+
+TEST(TreeTraversal, ForEachNodeNullStillRuns)
+{
+  RefPtr<ForEachTestNodeReverse> nullNode;
+  ForEachNode<layers::ReverseIterator>(
+      nullNode.get(),
+      [](ForEachTestNodeReverse* aNode) { return TraversalFlag::Continue; });
+}
+
+TEST(TreeTraversal, ForEachNodeAllEligible)
+{
+  std::vector<RefPtr<ForEachTestNodeForward>> nodeList;
+  int visitCount = 0;
+  nodeList.reserve(10);
+  for (int i = 0; i < 10; i++) {
+    nodeList.push_back(
+        new ForEachTestNodeForward(ForEachNodeType::Continue, i));
+  }
+
+  RefPtr<ForEachTestNodeForward> root = nodeList[0];
+  nodeList[0]->AddChild(nodeList[1]);
+  nodeList[0]->AddChild(nodeList[4]);
+  nodeList[1]->AddChild(nodeList[2]);
+  nodeList[1]->AddChild(nodeList[3]);
+  nodeList[4]->AddChild(nodeList[5]);
+  nodeList[4]->AddChild(nodeList[6]);
+  nodeList[6]->AddChild(nodeList[7]);
+  nodeList[7]->AddChild(nodeList[8]);
+  nodeList[7]->AddChild(nodeList[9]);
+
+  ForEachNode<layers::ForwardIterator>(
+      root.get(), [&visitCount](ForEachTestNodeForward* aNode) {
+        aNode->SetActualTraversalRank(visitCount);
+        visitCount++;
+        return aNode->GetType() == ForEachNodeType::Continue
+                   ? TraversalFlag::Continue
+                   : TraversalFlag::Skip;
+      });
+
+  for (size_t i = 0; i < nodeList.size(); i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+}
+
+TEST(TreeTraversal, ForEachNodeAllEligibleReverse)
+{
+  std::vector<RefPtr<ForEachTestNodeReverse>> nodeList;
+  int visitCount = 0;
+  nodeList.reserve(10);
+  for (int i = 0; i < 10; i++) {
+    nodeList.push_back(
+        new ForEachTestNodeReverse(ForEachNodeType::Continue, i));
+  }
+
+  RefPtr<ForEachTestNodeReverse> root = nodeList[0];
+  nodeList[0]->AddChild(nodeList[4]);
+  nodeList[0]->AddChild(nodeList[1]);
+  nodeList[1]->AddChild(nodeList[3]);
+  nodeList[1]->AddChild(nodeList[2]);
+  nodeList[4]->AddChild(nodeList[6]);
+  nodeList[4]->AddChild(nodeList[5]);
+  nodeList[6]->AddChild(nodeList[7]);
+  nodeList[7]->AddChild(nodeList[9]);
+  nodeList[7]->AddChild(nodeList[8]);
+
+  ForEachNode<layers::ReverseIterator>(
+      root.get(), [&visitCount](ForEachTestNodeReverse* aNode) {
+        aNode->SetActualTraversalRank(visitCount);
+        visitCount++;
+        return aNode->GetType() == ForEachNodeType::Continue
+                   ? TraversalFlag::Continue
+                   : TraversalFlag::Skip;
+      });
+
+  for (size_t i = 0; i < nodeList.size(); i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+}
+
+TEST(TreeTraversal, ForEachNodeSomeIneligibleNodes)
+{
+  std::vector<RefPtr<ForEachTestNodeForward>> expectedVisitedNodeList;
+  std::vector<RefPtr<ForEachTestNodeForward>> expectedSkippedNodeList;
+  int visitCount = 0;
+
+  expectedVisitedNodeList.push_back(
+      new ForEachTestNodeForward(ForEachNodeType::Continue, 0));
+  expectedVisitedNodeList.push_back(
+      new ForEachTestNodeForward(ForEachNodeType::Skip, 1));
+  expectedVisitedNodeList.push_back(
+      new ForEachTestNodeForward(ForEachNodeType::Continue, 2));
+  expectedVisitedNodeList.push_back(
+      new ForEachTestNodeForward(ForEachNodeType::Skip, 3));
+
+  expectedSkippedNodeList.push_back(
+      new ForEachTestNodeForward(ForEachNodeType::Continue));
+  expectedSkippedNodeList.push_back(
+      new ForEachTestNodeForward(ForEachNodeType::Continue));
+  expectedSkippedNodeList.push_back(
+      new ForEachTestNodeForward(ForEachNodeType::Skip));
+  expectedSkippedNodeList.push_back(
+      new ForEachTestNodeForward(ForEachNodeType::Skip));
+
+  RefPtr<ForEachTestNodeForward> root = expectedVisitedNodeList[0];
+  expectedVisitedNodeList[0]->AddChild(expectedVisitedNodeList[1]);
+  expectedVisitedNodeList[0]->AddChild(expectedVisitedNodeList[2]);
+  expectedVisitedNodeList[1]->AddChild(expectedSkippedNodeList[0]);
+  expectedVisitedNodeList[1]->AddChild(expectedSkippedNodeList[1]);
+  expectedVisitedNodeList[2]->AddChild(expectedVisitedNodeList[3]);
+  expectedVisitedNodeList[3]->AddChild(expectedSkippedNodeList[2]);
+  expectedVisitedNodeList[3]->AddChild(expectedSkippedNodeList[3]);
+
+  ForEachNode<layers::ForwardIterator>(
+      root.get(), [&visitCount](ForEachTestNodeForward* aNode) {
+        aNode->SetActualTraversalRank(visitCount);
+        visitCount++;
+        return aNode->GetType() == ForEachNodeType::Continue
+                   ? TraversalFlag::Continue
+                   : TraversalFlag::Skip;
+      });
+
+  for (size_t i = 0; i < expectedVisitedNodeList.size(); i++) {
+    ASSERT_EQ(expectedVisitedNodeList[i]->GetExpectedTraversalRank(),
+              expectedVisitedNodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  for (size_t i = 0; i < expectedSkippedNodeList.size(); i++) {
+    ASSERT_EQ(expectedSkippedNodeList[i]->GetExpectedTraversalRank(),
+              expectedSkippedNodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << "was not expected to be hit.";
+  }
+}
+
+TEST(TreeTraversal, ForEachNodeSomeIneligibleNodesReverse)
+{
+  std::vector<RefPtr<ForEachTestNodeReverse>> expectedVisitedNodeList;
+  std::vector<RefPtr<ForEachTestNodeReverse>> expectedSkippedNodeList;
+  int visitCount = 0;
+
+  expectedVisitedNodeList.push_back(
+      new ForEachTestNodeReverse(ForEachNodeType::Continue, 0));
+  expectedVisitedNodeList.push_back(
+      new ForEachTestNodeReverse(ForEachNodeType::Skip, 1));
+  expectedVisitedNodeList.push_back(
+      new ForEachTestNodeReverse(ForEachNodeType::Continue, 2));
+  expectedVisitedNodeList.push_back(
+      new ForEachTestNodeReverse(ForEachNodeType::Skip, 3));
+
+  expectedSkippedNodeList.push_back(
+      new ForEachTestNodeReverse(ForEachNodeType::Continue));
+  expectedSkippedNodeList.push_back(
+      new ForEachTestNodeReverse(ForEachNodeType::Continue));
+  expectedSkippedNodeList.push_back(
+      new ForEachTestNodeReverse(ForEachNodeType::Skip));
+  expectedSkippedNodeList.push_back(
+      new ForEachTestNodeReverse(ForEachNodeType::Skip));
+
+  RefPtr<ForEachTestNodeReverse> root = expectedVisitedNodeList[0];
+  expectedVisitedNodeList[0]->AddChild(expectedVisitedNodeList[2]);
+  expectedVisitedNodeList[0]->AddChild(expectedVisitedNodeList[1]);
+  expectedVisitedNodeList[1]->AddChild(expectedSkippedNodeList[1]);
+  expectedVisitedNodeList[1]->AddChild(expectedSkippedNodeList[0]);
+  expectedVisitedNodeList[2]->AddChild(expectedVisitedNodeList[3]);
+  expectedVisitedNodeList[3]->AddChild(expectedSkippedNodeList[3]);
+  expectedVisitedNodeList[3]->AddChild(expectedSkippedNodeList[2]);
+
+  ForEachNode<layers::ReverseIterator>(
+      root.get(), [&visitCount](ForEachTestNodeReverse* aNode) {
+        aNode->SetActualTraversalRank(visitCount);
+        visitCount++;
+        return aNode->GetType() == ForEachNodeType::Continue
+                   ? TraversalFlag::Continue
+                   : TraversalFlag::Skip;
+      });
+
+  for (size_t i = 0; i < expectedVisitedNodeList.size(); i++) {
+    ASSERT_EQ(expectedVisitedNodeList[i]->GetExpectedTraversalRank(),
+              expectedVisitedNodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+
+  for (size_t i = 0; i < expectedSkippedNodeList.size(); i++) {
+    ASSERT_EQ(expectedSkippedNodeList[i]->GetExpectedTraversalRank(),
+              expectedSkippedNodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << "was not expected to be hit.";
+  }
+}
+
+TEST(TreeTraversal, ForEachNodeIneligibleRoot)
+{
+  int visitCount = 0;
+
+  RefPtr<ForEachTestNodeReverse> root =
+      new ForEachTestNodeReverse(ForEachNodeType::Skip, 0);
+  RefPtr<ForEachTestNodeReverse> childNode1 =
+      new ForEachTestNodeReverse(ForEachNodeType::Continue);
+  RefPtr<ForEachTestNodeReverse> chlidNode2 =
+      new ForEachTestNodeReverse(ForEachNodeType::Skip);
+
+  ForEachNode<layers::ReverseIterator>(
+      root.get(), [&visitCount](ForEachTestNodeReverse* aNode) {
+        aNode->SetActualTraversalRank(visitCount);
+        visitCount++;
+        return aNode->GetType() == ForEachNodeType::Continue
+                   ? TraversalFlag::Continue
+                   : TraversalFlag::Skip;
+      });
+
+  ASSERT_EQ(root->GetExpectedTraversalRank(), root->GetActualTraversalRank())
+      << "Root was hit out of order.";
+  ASSERT_EQ(childNode1->GetExpectedTraversalRank(),
+            childNode1->GetActualTraversalRank())
+      << "Eligible child was still hit.";
+  ASSERT_EQ(chlidNode2->GetExpectedTraversalRank(),
+            chlidNode2->GetActualTraversalRank())
+      << "Ineligible child was still hit.";
+}
+
+TEST(TreeTraversal, ForEachNodeLeavesIneligible)
+{
+  std::vector<RefPtr<ForEachTestNodeForward>> nodeList;
+  nodeList.reserve(10);
+  int visitCount = 0;
+  for (int i = 0; i < 10; i++) {
+    if (i == 1 || i == 9) {
+      nodeList.push_back(new ForEachTestNodeForward(ForEachNodeType::Skip, i));
+    } else {
+      nodeList.push_back(
+          new ForEachTestNodeForward(ForEachNodeType::Continue, i));
+    }
+  }
+
+  RefPtr<ForEachTestNodeForward> root = nodeList[0];
+  nodeList[0]->AddChild(nodeList[1]);
+  nodeList[0]->AddChild(nodeList[2]);
+  nodeList[2]->AddChild(nodeList[3]);
+  nodeList[2]->AddChild(nodeList[4]);
+  nodeList[4]->AddChild(nodeList[5]);
+  nodeList[4]->AddChild(nodeList[6]);
+  nodeList[6]->AddChild(nodeList[7]);
+  nodeList[7]->AddChild(nodeList[8]);
+  nodeList[7]->AddChild(nodeList[9]);
+
+  ForEachNode<layers::ForwardIterator>(
+      root.get(), [&visitCount](ForEachTestNodeForward* aNode) {
+        aNode->SetActualTraversalRank(visitCount);
+        visitCount++;
+        return aNode->GetType() == ForEachNodeType::Continue
+                   ? TraversalFlag::Continue
+                   : TraversalFlag::Skip;
+      });
+
+  for (size_t i = 0; i < nodeList.size(); i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+}
+
+TEST(TreeTraversal, ForEachNodeLeavesIneligibleReverse)
+{
+  std::vector<RefPtr<ForEachTestNodeReverse>> nodeList;
+  nodeList.reserve(10);
+  int visitCount = 0;
+  for (int i = 0; i < 10; i++) {
+    if (i == 1 || i == 9) {
+      nodeList.push_back(new ForEachTestNodeReverse(ForEachNodeType::Skip, i));
+    } else {
+      nodeList.push_back(
+          new ForEachTestNodeReverse(ForEachNodeType::Continue, i));
+    }
+  }
+
+  RefPtr<ForEachTestNodeReverse> root = nodeList[0];
+  nodeList[0]->AddChild(nodeList[2]);
+  nodeList[0]->AddChild(nodeList[1]);
+  nodeList[2]->AddChild(nodeList[4]);
+  nodeList[2]->AddChild(nodeList[3]);
+  nodeList[4]->AddChild(nodeList[6]);
+  nodeList[4]->AddChild(nodeList[5]);
+  nodeList[6]->AddChild(nodeList[7]);
+  nodeList[7]->AddChild(nodeList[9]);
+  nodeList[7]->AddChild(nodeList[8]);
+
+  ForEachNode<layers::ReverseIterator>(
+      root.get(), [&visitCount](ForEachTestNodeReverse* aNode) {
+        aNode->SetActualTraversalRank(visitCount);
+        visitCount++;
+        return aNode->GetType() == ForEachNodeType::Continue
+                   ? TraversalFlag::Continue
+                   : TraversalFlag::Skip;
+      });
+
+  for (size_t i = 0; i < nodeList.size(); i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+}
+
+TEST(TreeTraversal, ForEachNodeLambdaReturnsVoid)
+{
+  std::vector<RefPtr<ForEachTestNodeReverse>> nodeList;
+  nodeList.reserve(10);
+  int visitCount = 0;
+  for (int i = 0; i < 10; i++) {
+    nodeList.push_back(
+        new ForEachTestNodeReverse(ForEachNodeType::Continue, i));
+  }
+
+  RefPtr<ForEachTestNodeReverse> root = nodeList[0];
+  nodeList[0]->AddChild(nodeList[4]);
+  nodeList[0]->AddChild(nodeList[1]);
+  nodeList[1]->AddChild(nodeList[3]);
+  nodeList[1]->AddChild(nodeList[2]);
+  nodeList[4]->AddChild(nodeList[6]);
+  nodeList[4]->AddChild(nodeList[5]);
+  nodeList[6]->AddChild(nodeList[7]);
+  nodeList[7]->AddChild(nodeList[9]);
+  nodeList[7]->AddChild(nodeList[8]);
+
+  ForEachNode<layers::ReverseIterator>(
+      root.get(), [&visitCount](ForEachTestNodeReverse* aNode) {
+        aNode->SetActualTraversalRank(visitCount);
+        visitCount++;
+      });
+
+  for (size_t i = 0; i < nodeList.size(); i++) {
+    ASSERT_EQ(nodeList[i]->GetExpectedTraversalRank(),
+              nodeList[i]->GetActualTraversalRank())
+        << "Node at index " << i << " was hit out of order.";
+  }
+}
+
+struct AssignSearchNodeTypesWithLastLeafAsNeedle {
+  RefPtr<SearchTestNodeForward>& node;
+  void operator()(SearchTestNodeForward* aNode) {
+    aNode->SetType(SearchNodeType::Hay);
+    if (aNode->IsLeaf()) {
+      node = aNode;
+    }
+  }
+};
+
+struct AssignSearchNodeTypesAllHay {
+  void operator()(SearchTestNode* aNode) {
+    aNode->SetType(SearchNodeType::Hay);
+  }
+};
+
+struct AssignSearchNodeTypesWithFirstLeafAsNeedle {
+  RefPtr<SearchTestNodeReverse>& needleNode;
+  void operator()(SearchTestNodeReverse* aNode) {
+    if (!needleNode && aNode->IsLeaf()) {
+      needleNode = aNode;
+    }
+    aNode->SetType(SearchNodeType::Hay);
+  }
+};
+
+struct AssignSearchNodeValuesAllFalseValuesReverse {
+  int falseValue;
+  RefPtr<SearchTestNodeReverse>& needleNode;
+  void operator()(SearchTestNodeReverse* aNode) {
+    aNode->SetValue(falseValue);
+    if (!needleNode && aNode->IsLeaf()) {
+      needleNode = aNode;
+    }
+  }
+};
+
+struct AssignSearchNodeValuesAllFalseValuesForward {
+  int falseValue;
+  RefPtr<SearchTestNodeForward>& needleNode;
+  void operator()(SearchTestNodeForward* aNode) {
+    aNode->SetValue(falseValue);
+    needleNode = aNode;
+  }
+};
+
+struct AllocateUnitRegionsToLeavesOnly {
+  int& xWrap;
+  int& squareCount;
+  void operator()(ForEachTestNode* aNode) {
+    if (aNode->IsLeaf()) {
+      int x = squareCount % xWrap;
+      int y = squareCount / xWrap;
+      aNode->SetRegion(nsRegion(nsRect(x, y, 1, 1)));
+      squareCount++;
+    }
+  }
+};
+
+template <typename Node>
+static RefPtr<Node> DepthFirstSearchForwardRecursive(RefPtr<Node> aNode) {
+  if (aNode->GetType() == SearchNodeType::Needle) {
+    return aNode;
+  }
+  for (RefPtr<Node> node = aNode->GetFirstChild(); node != nullptr;
+       node = node->GetNextSibling()) {
+    if (RefPtr<Node> foundNode = DepthFirstSearchForwardRecursive(node)) {
+      return foundNode;
+    }
+  }
+  return nullptr;
+}
+
+template <typename Node>
+static RefPtr<Node> DepthFirstSearchCaptureVariablesForwardRecursive(
+    RefPtr<Node> aNode, int a, int b, int c, int d, int e, int f, int g, int h,
+    int i, int j, int k, int l, int m, int& n, int& o, int& p, int& q, int& r,
+    int& s, int& t, int& u, int& v, int& w, int& x, int& y, int& z) {
+  if (aNode->GetValue() == a + b + c + d + e + f + g + h + i + j + k + l + m +
+                               n + o + p + q + r + s + t + u + v + w + x + y +
+                               z) {
+    return aNode;
+  }
+  for (RefPtr<Node> node = aNode->GetFirstChild(); node != nullptr;
+       node = node->GetNextSibling()) {
+    if (RefPtr<Node> foundNode =
+            DepthFirstSearchCaptureVariablesForwardRecursive(
+                node, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s,
+                t, u, v, w, x, y, z)) {
+      return foundNode;
+    }
+  }
+  return nullptr;
+}
+
+template <typename Node>
+static RefPtr<Node> DepthFirstSearchPostOrderForwardRecursive(
+    RefPtr<Node> aNode) {
+  for (RefPtr<Node> node = aNode->GetFirstChild(); node != nullptr;
+       node = node->GetNextSibling()) {
+    if (RefPtr<Node> foundNode =
+            DepthFirstSearchPostOrderForwardRecursive(node)) {
+      return foundNode;
+    }
+  }
+  if (aNode->GetType() == SearchNodeType::Needle) {
+    return aNode;
+  }
+  return nullptr;
+}
+
+template <typename Node>
+static RefPtr<Node> BreadthFirstSearchForwardQueue(RefPtr<Node> aNode) {
+  std::queue<RefPtr<Node>> nodes;
+  nodes.push(aNode);
+  while (!nodes.empty()) {
+    RefPtr<Node> node = nodes.front();
+    nodes.pop();
+    if (node->GetType() == SearchNodeType::Needle) {
+      return node;
+    }
+    for (RefPtr<Node> childNode = node->GetFirstChild(); childNode != nullptr;
+         childNode = childNode->GetNextSibling()) {
+      nodes.push(childNode);
+    }
+  }
+  return nullptr;
+}
+
+template <typename Node>
+static RefPtr<Node> DepthFirstSearchReverseRecursive(RefPtr<Node> aNode) {
+  if (aNode->GetType() == SearchNodeType::Needle) {
+    return aNode;
+  }
+  for (RefPtr<Node> node = aNode->GetLastChild(); node != nullptr;
+       node = node->GetPrevSibling()) {
+    if (RefPtr<Node> foundNode = DepthFirstSearchReverseRecursive(node)) {
+      return foundNode;
+    }
+  }
+  return nullptr;
+}
+
+template <typename Node>
+static RefPtr<Node> DepthFirstSearchCaptureVariablesReverseRecursive(
+    RefPtr<Node> aNode, int a, int b, int c, int d, int e, int f, int g, int h,
+    int i, int j, int k, int l, int m, int& n, int& o, int& p, int& q, int& r,
+    int& s, int& t, int& u, int& v, int& w, int& x, int& y, int& z) {
+  if (aNode->GetValue() == a + b + c + d + e + f + g + h + i + j + k + l + m +
+                               n + o + p + q + r + s + t + u + v + w + x + y +
+                               z) {
+    return aNode;
+  }
+  for (RefPtr<Node> node = aNode->GetLastChild(); node != nullptr;
+       node = node->GetPrevSibling()) {
+    if (RefPtr<Node> foundNode =
+            DepthFirstSearchCaptureVariablesReverseRecursive(
+                node, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s,
+                t, u, v, w, x, y, z)) {
+      return foundNode;
+    }
+  }
+  return nullptr;
+}
+
+template <typename Node>
+static RefPtr<Node> DepthFirstSearchPostOrderReverseRecursive(
+    RefPtr<Node> aNode) {
+  for (RefPtr<Node> node = aNode->GetLastChild(); node != nullptr;
+       node = node->GetPrevSibling()) {
+    if (RefPtr<Node> foundNode =
+            DepthFirstSearchPostOrderReverseRecursive(node)) {
+      return foundNode;
+    }
+  }
+  if (aNode->GetType() == SearchNodeType::Needle) {
+    return aNode;
+  }
+  return nullptr;
+}
+
+template <typename Node>
+static RefPtr<Node> BreadthFirstSearchReverseQueue(RefPtr<Node> aNode) {
+  std::queue<RefPtr<Node>> nodes;
+  nodes.push(aNode);
+  while (!nodes.empty()) {
+    RefPtr<Node> node = nodes.front();
+    nodes.pop();
+    if (node->GetType() == SearchNodeType::Needle) {
+      return node;
+    }
+    for (RefPtr<Node> childNode = node->GetLastChild(); childNode != nullptr;
+         childNode = childNode->GetPrevSibling()) {
+      nodes.push(childNode);
+    }
+  }
+  return nullptr;
+}