@Override
    public boolean persistent() {
        return internal.persistent();
    }
@Test
    public void shouldDelegatePersistent() {
        // `persistent = true` case
        when(inner.persistent()).thenReturn(true);
        assertThat(store.persistent(), is(true));

        // `persistent = false` case
        when(inner.persistent()).thenReturn(false);
        assertThat(store.persistent(), is(false));
    }