YGPersistentNodeCloningTest

Summary:
This adds a unit test to Yoga, which emulates the model of "persistent Yoga nodes" and cloning used by React Fabric, including the private (but relied on) Yoga APIs.

It models the over-invalidation exposed in D75287261, which reproduces (due to Yoga incorrectly measuring flex-basis under fit-content, and that constraint changing when sibling changes) but this test for now sets a definite height on A, to show that we only clone what is neccesary, when measure constraints do not have to change.

Having a minimal version of Fabric's model in Yoga unit tests should make some of these interesting interactions a bit easier to debug.

Changelog: [Internal]

Reviewed By: javache

Differential Revision: D75572762

Author: NickGerleman

tests/YGPersistentNodeCloningTest.cpp

@@ -0,0 +1,168 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <gtest/gtest.h>
+#include <yoga/Yoga.h>
+#include <yoga/config/Config.h>
+#include <yoga/node/Node.h>
+
+#include <functional>
+#include <memory>
+#include <vector>
+
+namespace facebook::yoga {
+
+struct YGPersistentNodeCloningTest : public ::testing::Test {
+  struct NodeWrapper {
+    NodeWrapper(
+        YGConfigRef config,
+        std::vector<std::shared_ptr<NodeWrapper>> children = {})
+        : node{YGNodeNewWithConfig(config)}, children{std::move(children)} {
+      YGNodeSetContext(node, this);
+
+      auto privateNode = resolveRef(node);
+      for (const auto& child : this->children) {
+        auto privateChild = resolveRef(child->node);
+        // Claim first ownership of not yet owned nodes, to avoid immediately
+        // cloning them
+        if (YGNodeGetOwner(child->node) == nullptr) {
+          privateChild->setOwner(privateNode);
+        }
+        privateNode->insertChild(privateChild, privateNode->getChildCount());
+      }
+    }
+
+    // Clone, with current children, for mutation
+    NodeWrapper(const NodeWrapper& other)
+        : node{YGNodeClone(other.node)}, children{other.children} {
+      YGNodeSetContext(node, this);
+
+      auto privateNode = resolveRef(node);
+      privateNode->setOwner(nullptr);
+    }
+
+    // Clone, with new children
+    NodeWrapper(
+        const NodeWrapper& other,
+        std::vector<std::shared_ptr<NodeWrapper>> children)
+        : node{YGNodeClone(other.node)}, children{std::move(children)} {
+      YGNodeSetContext(node, this);
+
+      auto privateNode = resolveRef(node);
+      privateNode->setOwner(nullptr);
+      privateNode->setChildren({});
+      privateNode->setDirty(true);
+
+      for (const auto& child : this->children) {
+        auto privateChild = resolveRef(child->node);
+        // Claim first ownership of not yet owned nodes, to avoid immediately
+        // cloning them
+        if (YGNodeGetOwner(child->node) == nullptr) {
+          privateChild->setOwner(privateNode);
+        }
+        privateNode->insertChild(privateChild, privateNode->getChildCount());
+      }
+    }
+
+    ~NodeWrapper() {
+      YGNodeFree(node);
+    }
+
+    YGNodeRef node;
+    std::vector<std::shared_ptr<NodeWrapper>> children;
+  };
+
+  struct ConfigWrapper {
+    ConfigWrapper() {
+      YGConfigSetCloneNodeFunc(
+          config,
+          [](YGNodeConstRef oldNode, YGNodeConstRef owner, size_t childIndex) {
+            onClone(oldNode, owner, childIndex);
+            auto wrapper = static_cast<NodeWrapper*>(YGNodeGetContext(owner));
+            auto old = static_cast<NodeWrapper*>(YGNodeGetContext(oldNode));
+
+            wrapper->children[childIndex] = std::make_shared<NodeWrapper>(*old);
+            return wrapper->children[childIndex]->node;
+          });
+    }
+
+    ~ConfigWrapper() {
+      YGConfigFree(config);
+    }
+
+    YGConfigRef config{YGConfigNew()};
+  };
+
+  ConfigWrapper configWrapper;
+  YGConfigRef config{configWrapper.config};
+
+  void SetUp() override {
+    onClone = [](...) {};
+  }
+
+  static inline std::function<void(YGNodeConstRef, YGNodeConstRef, size_t)>
+      onClone;
+};
+
+TEST_F(
+    YGPersistentNodeCloningTest,
+    changing_sibling_height_does_not_clone_neighbors) {
+  // <ScrollView>
+  //   <View id="Sibling" style={{ height: 1 }} />
+  //   <View id="A" style={{ height: 1 }}>
+  //     <View id="B">
+  //       <View id="C">
+  //         <View id="D"/>
+  //       </View>
+  //     </View>
+  //   </View>
+  // </ScrollView>
+
+  auto sibling = std::make_shared<NodeWrapper>(config);
+  YGNodeStyleSetHeight(sibling->node, 1);
+
+  auto d = std::make_shared<NodeWrapper>(config);
+  auto c = std::make_shared<NodeWrapper>(config, std::vector{d});
+  auto b = std::make_shared<NodeWrapper>(config, std::vector{c});
+  auto a = std::make_shared<NodeWrapper>(config, std::vector{b});
+  YGNodeStyleSetHeight(a->node, 1);
+
+  auto scrollContentView =
+      std::make_shared<NodeWrapper>(config, std::vector{sibling, a});
+  YGNodeStyleSetPositionType(scrollContentView->node, YGPositionTypeAbsolute);
+
+  auto scrollView =
+      std::make_shared<NodeWrapper>(config, std::vector{scrollContentView});
+  YGNodeStyleSetWidth(scrollView->node, 100);
+  YGNodeStyleSetHeight(scrollView->node, 100);
+
+  // We don't expect any cloning during the first layout
+  onClone = [](...) { FAIL(); };
+
+  YGNodeCalculateLayout(
+      scrollView->node, YGUndefined, YGUndefined, YGDirectionLTR);
+
+  auto siblingPrime = std::make_shared<NodeWrapper>(config);
+  YGNodeStyleSetHeight(siblingPrime->node, 2);
+
+  auto scrollContentViewPrime = std::make_shared<NodeWrapper>(
+      *scrollContentView, std::vector{siblingPrime, a});
+  auto scrollViewPrime = std::make_shared<NodeWrapper>(
+      *scrollView, std::vector{scrollContentViewPrime});
+
+  // We should only need to clone "A"
+  onClone = [&](YGNodeConstRef oldNode,
+                YGNodeConstRef /*owner*/,
+                size_t /*childIndex*/) {
+    EXPECT_EQ(YGNodeGetContext(oldNode), a.get());
+  };
+
+  YGNodeCalculateLayout(
+      scrollViewPrime->node, YGUndefined, YGUndefined, YGDirectionLTR);
+}
+
+} // namespace facebook::yoga