diff --git a/ReactCommon/fabric/core/BUCK b/ReactCommon/fabric/core/BUCK
index f394579fc..d9ee58fae 100644
--- a/ReactCommon/fabric/core/BUCK
+++ b/ReactCommon/fabric/core/BUCK
@@ -61,6 +61,7 @@ if not IS_OSS_BUILD:
     cxx_test(
         name = "tests",
         srcs = glob(["tests/**/*.cpp"]),
+        headers = glob(["tests/**/*.h"]),
         contacts = ["oncall+react_native@xmail.facebook.com"],
         compiler_flags = [
             "-fexceptions",
diff --git a/ReactCommon/fabric/core/componentdescriptor/ConcreteComponentDescriptor.h b/ReactCommon/fabric/core/componentdescriptor/ConcreteComponentDescriptor.h
index 0a521bd49..95de5e175 100644
--- a/ReactCommon/fabric/core/componentdescriptor/ConcreteComponentDescriptor.h
+++ b/ReactCommon/fabric/core/componentdescriptor/ConcreteComponentDescriptor.h
@@ -9,8 +9,9 @@
 
 #include <memory>
 
-#include <fabric/core/ShadowNode.h>
+#include <fabric/core/ComponentDescriptor.h>
 #include <fabric/core/Props.h>
+#include <fabric/core/ShadowNode.h>
 
 namespace facebook {
 namespace react {
diff --git a/ReactCommon/fabric/core/shadownode/ShadowNode.cpp b/ReactCommon/fabric/core/shadownode/ShadowNode.cpp
index 0dfb51e1e..04fb5d30f 100644
--- a/ReactCommon/fabric/core/shadownode/ShadowNode.cpp
+++ b/ReactCommon/fabric/core/shadownode/ShadowNode.cpp
@@ -39,6 +39,7 @@ ShadowNode::ShadowNode(
   SharedShadowNodeSharedList children
 ):
   tag_(shadowNode->tag_),
+  rootTag_(shadowNode->rootTag_),
   instanceHandle_(shadowNode->instanceHandle_),
   props_(props ? props : shadowNode->props_),
   children_(children ? children : shadowNode->children_),
diff --git a/ReactCommon/fabric/core/tests/ComponentDescriptorTest.cpp b/ReactCommon/fabric/core/tests/ComponentDescriptorTest.cpp
new file mode 100644
index 000000000..699642ce7
--- /dev/null
+++ b/ReactCommon/fabric/core/tests/ComponentDescriptorTest.cpp
@@ -0,0 +1,66 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * 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 "TestComponent.h"
+
+using namespace facebook::react;
+
+TEST(ComponentDescriptorTest, createShadowNode) {
+  SharedComponentDescriptor descriptor = std::make_shared<TestComponentDescriptor>();
+
+  ASSERT_EQ(descriptor->getComponentHandle(), typeid(TestShadowNode).hash_code());
+  ASSERT_STREQ(descriptor->getComponentName().c_str(), "Test");
+
+  RawProps raw;
+  raw["nativeID"] = "abc";
+  SharedShadowNode node = descriptor->createShadowNode(9, 1, (void *)NULL, raw);
+
+  ASSERT_EQ(node->getComponentHandle(), typeid(TestShadowNode).hash_code());
+  ASSERT_STREQ(node->getComponentName().c_str(), "Test");
+  ASSERT_EQ(node->getTag(), 9);
+  ASSERT_EQ(node->getRootTag(), 1);
+
+  // TODO(#27369757): getProps() doesn't work
+  // ASSERT_STREQ(node->getProps()->getNativeId().c_str(), "testNativeID");
+}
+
+TEST(ComponentDescriptorTest, cloneShadowNode) {
+  SharedComponentDescriptor descriptor = std::make_shared<TestComponentDescriptor>();
+
+  RawProps raw;
+  raw["nativeID"] = "abc";
+  SharedShadowNode node = descriptor->createShadowNode(9, 1, (void *)NULL, raw);
+  SharedShadowNode cloned = descriptor->cloneShadowNode(node);
+
+  ASSERT_EQ(cloned->getComponentHandle(), typeid(TestShadowNode).hash_code());
+  ASSERT_STREQ(cloned->getComponentName().c_str(), "Test");
+  ASSERT_EQ(cloned->getTag(), 9);
+  ASSERT_EQ(cloned->getRootTag(), 1);
+
+  // TODO(#27369757): getProps() doesn't work
+  // ASSERT_STREQ(cloned->getProps()->getNativeId().c_str(), "testNativeID");
+}
+
+TEST(ComponentDescriptorTest, appendChild) {
+  SharedComponentDescriptor descriptor = std::make_shared<TestComponentDescriptor>();
+
+  RawProps raw;
+  raw["nativeID"] = "abc";
+  SharedShadowNode node1 = descriptor->createShadowNode(1, 1, (void *)NULL, raw);
+  SharedShadowNode node2 = descriptor->createShadowNode(2, 1, (void *)NULL, raw);
+  SharedShadowNode node3 = descriptor->createShadowNode(3, 1, (void *)NULL, raw);
+
+  descriptor->appendChild(node1, node2);
+  descriptor->appendChild(node1, node3);
+
+  SharedShadowNodeSharedList node1Children = node1->getChildren();
+  ASSERT_EQ(node1Children->size(), 2);
+  ASSERT_EQ(node1Children->at(0), node2);
+  ASSERT_EQ(node1Children->at(1), node3);
+}
diff --git a/ReactCommon/fabric/core/tests/ShadowNodeTest.cpp b/ReactCommon/fabric/core/tests/ShadowNodeTest.cpp
index 75bc82e80..418938a49 100644
--- a/ReactCommon/fabric/core/tests/ShadowNodeTest.cpp
+++ b/ReactCommon/fabric/core/tests/ShadowNodeTest.cpp
@@ -11,29 +11,10 @@
 #include <fabric/core/ShadowNode.h>
 #include <gtest/gtest.h>
 
+#include "TestComponent.h"
+
 using namespace facebook::react;
 
-class TestProps : public Props {
-public:
-  TestProps() {
-    RawProps raw;
-    raw["nativeID"] = "testNativeID";
-    apply(raw);
-  }
-};
-using SharedTestProps = std::shared_ptr<const TestProps>;
-
-class TestShadowNode;
-using SharedTestShadowNode = std::shared_ptr<const TestShadowNode>;
-class TestShadowNode : public ConcreteShadowNode<TestProps> {
-public:
-  using ConcreteShadowNode::ConcreteShadowNode;
-
-  ComponentName getComponentName() const override {
-    return ComponentName("Test");
-  }
-};
-
 TEST(ShadowNodeTest, handleProps) {
   RawProps raw;
   raw["nativeID"] = "abc";
diff --git a/ReactCommon/fabric/core/tests/TestComponent.h b/ReactCommon/fabric/core/tests/TestComponent.h
new file mode 100644
index 000000000..18890daeb
--- /dev/null
+++ b/ReactCommon/fabric/core/tests/TestComponent.h
@@ -0,0 +1,50 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <memory>
+
+#include <fabric/core/ConcreteComponentDescriptor.h>
+#include <fabric/core/ConcreteShadowNode.h>
+#include <fabric/core/ShadowNode.h>
+
+using namespace facebook::react;
+
+/**
+ * This defines a set of TestComponent classes: Props, ShadowNode, ComponentDescriptor.
+ * To be used for testing purpose.
+ */
+
+class TestProps : public Props {
+public:
+  TestProps() {
+    RawProps raw;
+    raw["nativeID"] = "testNativeID";
+    apply(raw);
+  }
+};
+using SharedTestProps = std::shared_ptr<const TestProps>;
+
+class TestShadowNode;
+using SharedTestShadowNode = std::shared_ptr<const TestShadowNode>;
+class TestShadowNode : public ConcreteShadowNode<TestProps> {
+public:
+  using ConcreteShadowNode::ConcreteShadowNode;
+
+  ComponentName getComponentName() const override {
+    return ComponentName("Test");
+  }
+};
+
+class TestComponentDescriptor: public ConcreteComponentDescriptor<TestShadowNode> {
+public:
+  // TODO (shergin): Why does this gets repeated here and the shadow node class?
+  ComponentName getComponentName() const override {
+    return "Test";
+  }
+};