Catch2: How to integrate Catch2 with NDK?

[zwcloud]

I don't think we can Supplying main() yourself in NDK environment. There is no main entry point function in a NDK lib.

Following is what I have done to use Catch2 in a NDK based lib.

__native-lib.cpp__

#define CATCH_CONFIG_RUNNER
#include "catch.hpp"

extern "C"
JNIEXPORT JNICALL
int Java_com_example_someproj_MyTest_runTest(JNIEnv *env, jclass type) {
    char *argv[] = {"whatever"};
    int result = Catch::Session().run(1, argv);//fake `argc` and `argv`
    return result;
}

unsigned int Factorial( unsigned int number ) {
    return number <= 1 ? number : Factorial(number-1)*number;
}

//some example tests
TEST_CASE( "Factorials are computed", "[factorial]" ) {
    REQUIRE( Factorial(1) == 1 );
    REQUIRE( Factorial(2) == 2 );
    REQUIRE( Factorial(3) == 6 );
    REQUIRE( Factorial(10) == 3628800 );
}

__MyTest.java__

package com.example.someproj;

public class MyTest {
    static {
        System.loadLibrary("native-lib");
    }
    public void runNativeTest() {//this is called somewhere to execute Catch2 tests
        assertTrue("Some test doesn't not past.", 0 == runTest());
    }

    public static native int runTest();
}

[horenmar]

I am sorry, but I don't understand what is the issue here?

The important part of the "own main" documentation is how to set up a Session and then let Catch run the tests. It is part of main because that is the auto-run section in most environments. It might be worth adding some notes to documentation about this though.

[janisozaur]

There is no need to supply the Java-based entrypoint, native (as in: comprised solely of C++ code) binaries work fine. You should be able to provide a regular main() function and execute your application through it.

[zwcloud]

@horenmar
No all people uses auto-run unit tests all the time. For me, I write small unit tests when developing my app, just to ensure that I haven't done anything wrong in the small section of code I just wrote. People call this TDD you know. In this case, I just want to click a button and run a test case.

@janisozaur

There is no need to supply the Java-based entrypoint, native (as in: comprised solely of C++ code) binaries work fine.

It may work, but it is far from working Fine. That's how I work with the Android Studio, a java unit test method allows me to click the button and run a unit test in the IDE.

You should be able to provide a regular main() function and execute your application through it.

No. I'm not able to do that. Because a java-based Android app doesn't expose the main() function. (Even a NativeActivity-based Android app doesn't expose the main function.) If you can achieve that, I'll appreciate it if you tell me how to do it.

[zwcloud]

Below is how I use it in a practical Android project in Android Studio:

The red-circled ▶ is the "button" I can click to run a unit test with specific test name.

And the testName is passed to a jni function runTest:

extern "C" JNIEXPORT JNICALL
int Java_cn_easyar_androidaudiondk_ExampleInstrumentedTest_runTest(JNIEnv *env, jclass type, jstring testName_) {

    auto buf = std::make_shared<androidbuf>();
    std::cout.rdbuf(buf.get());

    //https://github.com/catchorg/Catch2/blob/master/docs/command-line.md#specifying-which-tests-to-run
    const char *arguments[] = {
            "fake.exe",
            jstring_to_string(env, testName_).c_str()
    };
    int argc = 2;
    auto argv = const_cast<char**>(arguments);
    int result = Catch::Session().run(argc, argv);

    return result;
}

And the test code:

[zimtkeks]

@zwcloud Thanks for sharing, that's exactly the kind of setup that I was looking for.

I also think that it is a completely valid setup for Android developers, for the same reasons given by @zwcloud . This would be a valuable addition to the Catch docs.