@Test
public void releaseDelegatesToReleaseCallback() {

    // given
    SimpleInputBuffer buffer = mock(SimpleInputBuffer.class);
    ReleaseCallback releaseCallback = mock(ReleaseCallback.class);
    ItemSource<SimpleInputBuffer> itemSource = new InputBufferItemSource(buffer, releaseCallback);
    // when
    itemSource.release();
    // then
    verify(releaseCallback, times(1)).completed(eq(itemSource));
}