Problem getting native code to work in a module in Android Studio

Question

I'm trying to build an Android library that has a combo of native code and Java code calling the C++ code. The C++ is stictly limited to the library. I managed to get a project compiling, but when I launch the unit testing, I get an exception that it cannot find the library.
I checked and the code does generate the.so files, but they just can't be found.

So, I created an empty activity project and created in it a module for an Android library. In it, I placed my code in the src/main/cpp directory, along with a CMakeLists.txt file:
libnative.cpp :

#include "libnativeJNI.h"

#ifdef __cplusplus
extern "C" {
#endif

JNIEXPORT jint JNICALL GEN_FUNCNAME(TestFunction)(JNIEnv *jenv, jobject jobj)
{
    return 0;
}

#ifdef __cplusplus
}
#endif

libnative.h :

#ifndef NDKTROUBLESHOOT_LIBNATIVEJNI_H
#define NDKTROUBLESHOOT_LIBNATIVEJNI_H

#include "jni.h"
#define GEN_FUNCNAME(FUNCNAME) Java_com_java_libnative_libnative_##FUNCNAME

#endif //NDKTROUBLESHOOT_LIBNATIVEJNI_H

CMakeLists.txt :

cmake_minimum_required(VERSION 3.10.2)
project("LibNative")
add_library(LibNative SHARED libnativeJNI.cpp)
find_library(log-lib log)
target_link_libraries(LibNative ${log-lib})

I also updated gradle inside the module to compile the native code by adding the following lines in the android section:

    externalNativeBuild {
        cmake {
            path file('src/main/cpp/CMakeLists.txt')
        }
    }

The native code is linked to the Java class in src/main/java/com/java/libnative/ :
libnative.java :

package com.java.libnative;

public class libnative {
    static
    {
        System.loadLibrary("LibNative");
    }

    private native int TestFunction();

    public libnative()
    {
        TestFunction();
    }
}

I can also see the native code being compiled in a library as libnative/build/intermediates/cmake/debug/obj/{Architecture}/libLibNative.so .

Now, the IDE recognizes the native functions, but I created a unit test in the module to test if it actually works:

package com.java.libnative;
import org.junit.Test;

public class UnitTest {
    @Test
    public void library_canLoad()
    {
        new libnative();
    }
}

However, doing so triggers an exception on run:

java.lang.UnsatisfiedLinkError: no libnative in java.library.path

What am I missing to make this work?

Answer 1

Turns out, as mentioned by Michael , that the test environment doesn't support the loading of a native library. I tested the same code by sending it to a phone bundled in an app and it worked fine.
Therefore in this case, the unit testing cannot be used to test the library unfortunately.