@Test
public void shouldReturnNullOutputStream() {

    // given
    when(delegate.put(any(), any())).thenReturn(null);
    ContentCache contentCache = new ZippedContentCache(delegate);
    // when
    final OutputStream stream = contentCache.put(() -> StringUtils.EMPTY, ContentCache.TimeToLive.DEFAULT);
    // then
    verify(delegate, times(1)).put(any(), any());
    assertNull(stream);
}