Android methods are not mocked when using Mockito

I'm writing a test which purpose is to test some methods in subclass of Adapter class (used by RecyclerView). To mock adapter behavior I've chosen Mockito library.

Here's a simple test:

import android.support.v7.widget.RecyclerView.Adapter;

public class TestAdapter {

    @Test
    public void testAdapter() throws Exception {
        Adapter adapter = Mockito.mock(Adapter.class);

        adapter.notifyDataSetChanged();
    }
}

Nothing should happen but NullPointerException is thrown instead.

java.lang.NullPointerException
    at android.support.v7.widget.RecyclerView$Adapter.notifyDataSetChanged(RecyclerView.java:5380)
    at pl.toro.test.adapter.TestAdapter.testAdapter(TestAdapter.java:38)
    ...

I've also tried with spy instead of mock

@Test
public void testAdapterWithDoNothing() throws Exception {
    Adapter adapter = Mockito.spy(new Adapter() {...});
    doNothing().when(adapter).notifyDataSetChanged();
}

But this fails at second line (notice this is just a mock setup)

java.lang.NullPointerException
    at android.support.v7.widget.RecyclerView$AdapterDataObservable.notifyChanged(RecyclerView.java:8946)
    at android.support.v7.widget.RecyclerView$Adapter.notifyDataSetChanged(RecyclerView.java:5380)
    at pl.toro.test.adapter.TestAdapter.testAdapterWithDoNothing(TestAdapter.java:59)
    ...

Is it possible to mock support classes with Mockito in unit tests?