Add test utilities for C++ and Java

Summary:
@public

Test utility on top of the new event system that maintains a counter of instantiated nodes. Meant to replace the global node counter.

Reviewed By: SidharthGuglani

Differential Revision: D15174855

fbshipit-source-id: 6998472f95a09b8da652257a26596164bdcf43d6

testutil/BUCK

@@ -0,0 +1,37 @@
+load("//tools/build_defs/oss:yoga_defs.bzl", "ANDROID", "FBJNI_TARGET", "LIBRARY_COMPILER_FLAGS", "SOLOADER_TARGET", "yoga_cxx_library", "yoga_dep", "yoga_java_library")
+
+yoga_cxx_library(
+    name = "testutil",
+    srcs = ["testutil.cpp"],
+    header_namespace = "yoga/testutil",
+    exported_headers = ["testutil.h"],
+    compiler_flags = LIBRARY_COMPILER_FLAGS,
+    soname = "libyoga_testutil.$(ext)",
+    visibility = ["PUBLIC"],
+    deps = [yoga_dep(":yoga")],
+)
+
+yoga_java_library(
+    name = "java",
+    srcs = ["TestUtil.java"],
+    source = "1.7",
+    target = "1.7",
+    visibility = ["PUBLIC"],
+    deps = [
+        ":jni",
+        SOLOADER_TARGET,
+    ],
+)
+
+yoga_cxx_library(
+    name = "jni",
+    srcs = ["jni.cpp"],
+    compiler_flags = LIBRARY_COMPILER_FLAGS,
+    platforms = ANDROID,
+    soname = "libyoga_testutil_jni.$(ext)",
+    visibility = ["PUBLIC"],
+    deps = [
+        ":testutil",
+        FBJNI_TARGET,
+    ],
+)

testutil/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();
+}

testutil/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 <fb/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/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 "testutil.h"
+
+#include <yoga/YGNode.h>
+#include <yoga/events.h>
+
+#include <utility>
+
+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();
+  return std::exchange(nodeInstanceCount, 0);
+}
+
+ScopedEventSubscription::ScopedEventSubscription(
+    std::function<Event::Subscriber>&& s) {
+  Event::subscribe(std::move(s));
+}
+
+ScopedEventSubscription::~ScopedEventSubscription() {
+  Event::reset();
+}
+
+} // namespace test
+} // namespace yoga
+} // namespace facebook

testutil/testutil.h

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+/**
+ * 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/events.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