@Test
public void testCloseClosesUnderlyingStreamForASingle() throws Exception {

    InputStream a = mock(InputStream.class);
    ImmutableList<InputStream> inputStreams = ImmutableList.of(a);
    ConcatClosingInputStream concatClosingInputStream = new ConcatClosingInputStream(inputStreams.iterator());
    concatClosingInputStream.close();
    verify(a).close();
}