Migrate unit-test to RegisterNatives.

Author: DanAlbert

unit-test/app/build.gradle

@@ -47,6 +47,7 @@ android {
 }
 
 dependencies {
+    implementation project(":base")
     implementation libs.appcompat
     implementation libs.material
     implementation libs.androidx.constraintlayout

unit-test/app/src/main/cpp/CMakeLists.txt

@@ -8,49 +8,25 @@ project("unittest")
 
 include(AppLibrary)
 
+find_package(base REQUIRED CONFIG)
 find_package(googletest REQUIRED CONFIG)
 find_package(junit-gtest REQUIRED CONFIG)
 
 add_app_library(adder OBJECT adder.cpp)
 
-# Creates and names a library, sets it as either STATIC
-# or SHARED, and provides the relative paths to its source code.
-# You can define multiple libraries, and CMake builds them for you.
-# Gradle automatically packages shared libraries with your APK.
-
-add_app_library( # Sets the name of the library.
+add_app_library(
     unittest
-
-    # Sets the library as a shared library.
     SHARED
-
-    # Provides a relative path to your source file(s).
     $<TARGET_OBJECTS:adder>
-    native-lib.cpp)
-
-# Searches for a specified prebuilt library and stores the path as a
-# variable. Because CMake includes system libraries in the search path by
-# default, you only need to specify the name of the public NDK library
-# you want to add. CMake verifies that the library exists before
-# completing its build.
-
-find_library( # Sets the name of the path variable.
-    log-lib
-
-    # Specifies the name of the NDK library that
-    # you want CMake to locate.
-    log)
-
-# Specifies libraries CMake should link to your target library. You
-# can link multiple libraries, such as libraries you define in this
-# build script, prebuilt third-party libraries, or system libraries.
+    native-lib.cpp
+)
 
 target_link_libraries( # Specifies the target library.
     unittest
-
-    # Links the target library to the log library
-    # included in the NDK.
-    ${log-lib})
+    PRIVATE
+    base::base
+    log
+)
 
 add_app_library(app_tests SHARED adder_test.cpp)
 target_link_libraries(app_tests

unit-test/app/src/main/cpp/native-lib.cpp

@@ -1,8 +1,25 @@
+#include <base/macros.h>
 #include <jni.h>
 
 #include "adder.h"
 
-extern "C" JNIEXPORT jint JNICALL
-Java_com_example_unittest_MainActivity_add(JNIEnv*, jobject, jint a, jint b) {
-  return add((int)a, (int)b);
-}
+jint Add(JNIEnv*, jobject, jint a, jint b) { return add((int)a, (int)b); }
+
+extern "C" JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM* _Nonnull vm,
+                                             void* _Nullable) {
+  JNIEnv* env;
+  if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6) != JNI_OK) {
+    return JNI_ERR;
+  }
+
+  jclass c = env->FindClass("com/example/unittest/MainActivity");
+  if (c == nullptr) return JNI_ERR;
+
+  static const JNINativeMethod methods[] = {
+      {"add", "(II)I", reinterpret_cast<void*>(Add)},
+  };
+  int rc = env->RegisterNatives(c, methods, arraysize(methods));
+  if (rc != JNI_OK) return rc;
+
+  return JNI_VERSION_1_6;
+}