add simple native test

Author: Vladimir Kocheryzhkin

visionSamples/FaceTracker/app/build.gradle

@@ -20,7 +20,7 @@ android {
         externalNativeBuild {
             cmake {
                 cppFlags "-frtti -fexceptions"
-                abiFilters 'x86', 'x86_64', 'armeabi', 'armeabi-v7a'
+                abiFilters 'x86', 'x86_64', 'armeabi-v7a'
                 arguments "-DANDROID_STL=c++_shared"
                 // Passes optional arguments to CMake.
                 //arguments "-DANDROID_ARM_NEON=TRUE", "-DANDROID_TOOLCHAIN=clang"
@@ -54,18 +54,15 @@ android {
 }
 
 dependencies {
-    implementation 'com.android.support:support-annotations:27.1.1'
-
     androidTestImplementation 'junit:junit:4.12'
+    implementation 'com.android.support:support-annotations:27.1.1'
     androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
     androidTestImplementation 'com.android.support.test:runner:1.0.2'
     androidTestImplementation 'com.android.support.test:rules:1.0.2'
     androidTestImplementation 'org.hamcrest:hamcrest-library:1.3'
-
     implementation fileTree(include: ['*.jar'], dir: 'libs')
     implementation 'com.android.support:support-v4:23.4.0'
     implementation 'com.android.support:design:23.4.0'
     implementation 'com.google.android.gms:play-services-vision:9.4.0+'
     implementation 'com.shamanland:xdroid-toaster:0.2.4'
-    
 }

visionSamples/FaceTracker/app/src/androidTest/java/com/google/android/gms/samples/vision/face/facetracker/ExampleInstrumentedTest.java

@@ -2,8 +2,10 @@
 
 import android.content.Context;
 import android.support.test.InstrumentationRegistry;
+import android.support.test.rule.ActivityTestRule;
 import android.support.test.runner.AndroidJUnit4;
 
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -16,4 +18,15 @@ public void useAppContext() throws Exception {
         Context appContext = InstrumentationRegistry.getTargetContext();
         assertEquals("com.google.android.gms.samples.vision.face.facetracker", appContext.getPackageName());
     }
+
+
+    @Rule
+    public ActivityTestRule<FaceTrackerActivity> activityRule = new ActivityTestRule(FaceTrackerActivity.class);
+
+    @Test
+    public void callAddContext()  {
+        FaceTrackerActivity activity  = activityRule.getActivity();
+        int res = activity.nativeAdd(1,2);
+        assertEquals(3, res);
+    }
 }

visionSamples/FaceTracker/app/src/main/cpp/native-lib.cpp

@@ -287,4 +287,11 @@ Java_com_google_android_gms_samples_vision_face_facetracker_FaceTrackerActivity_
 
     AndroidBitmap_unlockPixels(env, bmp);
     return env->NewStringUTF(returnValue.c_str());
+}extern "C"
+JNIEXPORT jint JNICALL
+Java_com_google_android_gms_samples_vision_face_facetracker_FaceTrackerActivity_nativeAdd(
+        JNIEnv *env, jobject instance, jint a, jint b) {
+
+    return a + b;
+
 }

visionSamples/FaceTracker/app/src/main/java/com/google/android/gms/samples/vision/face/facetracker/FaceTrackerActivity.java

@@ -444,4 +444,5 @@ public void onDone() {
 
     public native int loadResources();
     public native String recognizeFromImage(Bitmap bmp);
+    public native int nativeAdd(int a, int b);
 }