@Test
void checkSimple() {

    final Function<T, S> f = o -> null;
    final PaginatedApi<S, T> p = spy(new PaginatedApi<>(null, null, null, null));
    doReturn(null).when(p)
        .execute(eq(f), any(), anyBoolean());
    p.execute(f);
    verify(p).execute(eq(f), isNotNull(), eq(true));
}