Rxjava: 2.X Null object reference on Completable.test() with Mockito

[JuanDavid31]

Hello, I'm actually having the following issue:

java.lang.NullPointerException: Attempt to invoke virtual method 'io.reactivex.observers.TestObserver io.reactivex.Completable.test()' on a null object reference
at repositorio.RepositorioProductoTest.insertarProductoTest(RepositorioProductoTest.java:48)

While testing a Completable in my code

    @Test
    public void insertarProductoTest(){
        repo.agregarElemento(productoDummy)
            .test()
            .assertComplete();

        verify(repo).darInstanciaDB().darDaoProducto().agregarProducto(argumentCaptor.capture());
        assertThat(argumentCaptor.getValue().getNombre(), Matchers.is("producto"));
    }

repo variable is being mocked with the @Mocked anotattion
And if it is useful, here is the .agregarElemento(...) method

   public Completable agregarElemento(Producto elemento) {
        return Completable.fromAction(()-> darInstanciaDB().darDaoProducto().agregarProducto(elemento));
    }

I'm following this as example
https://github.com/googlesamples/android-architecture-components/blob/master/BasicRxJavaSample/app/src/test/java/com/example/android/observability/UserViewModelTest.java

Hope you can help me.

[JakeWharton]

The Completable reference is null per the exception. This doesn't have anything to do with RxJava.

[akarnokd]

Most likely you have the wrong or missing mocking of your object or method calls. Please ask this question on StackOverflow under the mockito tag.

[jorgehenao09]

Juan David, pudo encontrar la forma de probar el metodo? tengo exactamente el mismo incoveniente con un metodo igual. Gracias

[JuanDavid31]

Hola Jorge, la verdad no pude solucionarlo; hasta ahí deje el problema. Que tenga suerte solucionandolo.