Fabric: Making ComponentBuilder copyable and movable

Summary:
It's useful property to have.

Changelog: [Internal] Fabric-specific internal change.

Reviewed By: sammy-SC

Differential Revision: D19596280

fbshipit-source-id: 5b60cc4f7c65c3458ff35ffa2dfaafce79dc985a

Author: shergin

ReactCommon/fabric/element/ComponentBuilder.h

@@ -29,6 +29,14 @@ class ComponentBuilder final {
   ComponentBuilder(
       ComponentDescriptorRegistry::Shared const &componentDescriptorRegistry);
 
+  /*
+   * Copyable and movable.
+   */
+  ComponentBuilder(ComponentBuilder const &componentBuilder) = default;
+  ComponentBuilder(ComponentBuilder &&componentBuilder) noexcept = default;
+  ComponentBuilder &operator=(ComponentBuilder const &other) = default;
+  ComponentBuilder &operator=(ComponentBuilder &&other) = default;
+
   /*
    * Builds a `ShadowNode` tree with given `Element` tree using stored
    * `ComponentDescriptorRegistry`.

ReactCommon/fabric/element/testUtils.h

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * 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 <react/components/root/RootComponentDescriptor.h>
+#include <react/components/view/ViewComponentDescriptor.h>
+#include <react/element/ComponentBuilder.h>
+#include <react/uimanager/ComponentDescriptorProviderRegistry.h>
+
+namespace facebook {
+namespace react {
+
+extern ComponentBuilder simpleComponentBuilder() {
+  ComponentDescriptorProviderRegistry componentDescriptorProviderRegistry{};
+  auto eventDispatcher = EventDispatcher::Shared{};
+  auto componentDescriptorRegistry =
+      componentDescriptorProviderRegistry.createComponentDescriptorRegistry(
+          ComponentDescriptorParameters{eventDispatcher, nullptr, nullptr});
+
+  componentDescriptorProviderRegistry.add(
+      concreteComponentDescriptorProvider<RootComponentDescriptor>());
+  componentDescriptorProviderRegistry.add(
+      concreteComponentDescriptorProvider<ViewComponentDescriptor>());
+
+  return ComponentBuilder{componentDescriptorRegistry};
+}
+
+} // namespace react
+} // namespace facebook

ReactCommon/fabric/element/tests/ElementTest.cpp

@@ -12,21 +12,13 @@
 #include <react/components/view/ViewComponentDescriptor.h>
 #include <react/element/ComponentBuilder.h>
 #include <react/element/Element.h>
+#include <react/element/testUtils.h>
 #include <react/uimanager/ComponentDescriptorProviderRegistry.h>
 
 using namespace facebook::react;
 
 TEST(ElementTest, testNormalCases) {
-  ComponentDescriptorProviderRegistry componentDescriptorProviderRegistry{};
-  auto eventDispatcher = EventDispatcher::Shared{};
-  auto componentDescriptorRegistry =
-      componentDescriptorProviderRegistry.createComponentDescriptorRegistry(
-          ComponentDescriptorParameters{eventDispatcher, nullptr, nullptr});
-
-  componentDescriptorProviderRegistry.add(
-      concreteComponentDescriptorProvider<ViewComponentDescriptor>());
-
-  auto builder = ComponentBuilder{componentDescriptorRegistry};
+  auto builder = simpleComponentBuilder();
 
   auto shadowNodeA = std::shared_ptr<ViewShadowNode const>{};
   auto shadowNodeAA = std::shared_ptr<ViewShadowNode const>{};