@Override
    synchronized int numBuffered() {
        return wrapped.numBuffered();
    }
@Test
    public void testNumBuffered() {
        final int numBuffered = 1;
        when(wrapped.numBuffered()).thenReturn(numBuffered);

        final int result = synchronizedPartitionGroup.numBuffered();

        assertEquals(numBuffered, result);
        verify(wrapped, times(1)).numBuffered();
    }