fix gradle compliation (#925)

Summary:
Pull Request resolved: https://github.com/facebook/yoga/pull/925

Gradle is failing to compile yoga for two reasons:
1. Ever since `YogaNodeJNIPhantomRefs` was introduced which uses `DestructorThread.Destructor` from fbjni which was the first direct Java dependency from yoga java to fbjni java code.

2. Adding a missing gradle endpoint for `testutil` since it is now required for yoga unit-tests

Reviewed By: SidharthGuglani

Differential Revision: D17274226

fbshipit-source-id: 3df9648321162d34f81fd3675ca1474e8a1c6d3a

testutil/src/main/AndroidManifest.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<!--
+  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.
+-->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+  package="com.facebook.yoga.testutil">
+</manifest>

testutil/src/main/cpp/CMakeLists.txt

@@ -0,0 +1,30 @@
+#
+# 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.
+#
+
+cmake_minimum_required(VERSION 3.4.1)
+
+set(CMAKE_VERBOSE_MAKEFILE on)
+
+add_compile_options(
+    -fno-omit-frame-pointer
+    -fexceptions
+    -Wall
+    -std=c++11
+    -DDISABLE_CPUCAP
+    -DDISABLE_XPLAT)
+
+file(GLOB testutil_SRC
+    jni/*.cpp
+    testutil/*.cpp)
+
+add_library(testutil SHARED
+    ${testutil_SRC})
+
+target_include_directories(testutil PRIVATE
+    include)
+
+target_link_libraries(testutil android log)

testutil/src/main/cpp/include/yoga/testutil/testutil.h

@@ -0,0 +1,30 @@
+/*
+ * 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 <yoga/event/event.h>
+
+#include <functional>
+
+namespace facebook {
+namespace yoga {
+namespace test {
+
+struct TestUtil {
+  static void startCountingNodes();
+  static int nodeCount();
+  static int stopCountingNodes();
+};
+
+struct ScopedEventSubscription {
+  ScopedEventSubscription(std::function<Event::Subscriber>&&);
+  ~ScopedEventSubscription();
+};
+
+} // namespace test
+} // namespace yoga
+} // namespace facebook

testutil/src/main/cpp/jni/jni.cpp

@@ -0,0 +1,38 @@
+/*
+ * 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.
+ */
+#include <fbjni/fbjni.h>
+#include <yoga/testutil/testutil.h>
+
+using namespace facebook;
+
+namespace {
+
+void startCountingNodes(jni::alias_ref<jclass>) {
+  yoga::test::TestUtil::startCountingNodes();
+}
+
+jint nodeCount(jni::alias_ref<jclass>) {
+  return yoga::test::TestUtil::nodeCount();
+}
+
+jint stopCountingNodes(jni::alias_ref<jclass>) {
+  return yoga::test::TestUtil::stopCountingNodes();
+}
+
+} // namespace
+
+jint JNI_OnLoad(JavaVM* vm, void*) {
+  return jni::initialize(vm, [] {
+    jni::registerNatives(
+        "com/facebook/yoga/TestUtil",
+        {
+            makeNativeMethod("startCountingNodes", startCountingNodes),
+            makeNativeMethod("nodeCount", nodeCount),
+            makeNativeMethod("stopCountingNodes", stopCountingNodes),
+        });
+  });
+}

testutil/src/main/cpp/testutil/testutil.cpp

@@ -0,0 +1,65 @@
+/*
+ * 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.
+ */
+#include <yoga/testutil/testutil.h>
+
+#include <yoga/YGNode.h>
+#include <yoga/event/event.h>
+
+namespace facebook {
+namespace yoga {
+namespace test {
+
+int nodeInstanceCount = 0;
+
+namespace {
+
+void yogaEventSubscriber(
+    const YGNode& node,
+    Event::Type eventType,
+    const Event::Data& eventData) {
+
+  switch (eventType) {
+    case Event::NodeAllocation:
+      nodeInstanceCount++;
+      break;
+    case Event::NodeDeallocation:
+      nodeInstanceCount--;
+      break;
+    default:
+      break;
+  }
+}
+} // namespace
+
+void TestUtil::startCountingNodes() {
+  nodeInstanceCount = 0;
+  Event::subscribe(yogaEventSubscriber);
+}
+
+int TestUtil::nodeCount() {
+  return nodeInstanceCount;
+}
+
+int TestUtil::stopCountingNodes() {
+  Event::reset();
+  auto prev = nodeInstanceCount;
+  nodeInstanceCount = 0;
+  return prev;
+}
+
+ScopedEventSubscription::ScopedEventSubscription(
+    std::function<Event::Subscriber>&& s) {
+  Event::subscribe(std::move(s));
+}
+
+ScopedEventSubscription::~ScopedEventSubscription() {
+  Event::reset();
+}
+
+} // namespace test
+} // namespace yoga
+} // namespace facebook

testutil/src/main/java/com/facebook/yoga/TestUtil.java

@@ -0,0 +1,19 @@
+/*
+ * 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.
+ */
+package com.facebook.yoga;
+
+import com.facebook.soloader.SoLoader;
+
+class TestUtil {
+  static {
+    SoLoader.loadLibrary("yoga_testutil_jni");
+  }
+
+  static native void startCountingNodes();
+  static native int nodeCount();
+  static native int stopCountingNodes();
+}