Reorgnaize C++ tests

Summary:
This does some preprataion for the Yoga CMake Build. The main change is removing the dedicated testutil top-level-directory and static library. This contains a method to count nodes using the event functions exposed to C++, along with a Java binding for the test utility (since the events don't have a Java binding). It is only used in a single place in a way that isn't very useful, so it simplifies things to treat is as source in the existing C++ test library.

This also separates the hand-written and generated UTs, like we are doing in the JS directory in D42207782.

Reviewed By: christophpurrer

Differential Revision: D42247762

fbshipit-source-id: f8a270e99d0315ba7fc608f2471333e7a7be9d79

tests/util/TestUtil.h

@@ -0,0 +1,31 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <yoga/event/event.h>
+
+#include <functional>
+
+namespace facebook {
+namespace yoga {
+namespace test {
+
+struct YOGA_EXPORT TestUtil {
+  static void startCountingNodes();
+  static int nodeCount();
+  static int stopCountingNodes();
+};
+
+struct ScopedEventSubscription {
+  ScopedEventSubscription(std::function<Event::Subscriber>&&);
+  ~ScopedEventSubscription();
+};
+
+} // namespace test
+} // namespace yoga
+} // namespace facebook