@Override
    public Checksum compute(final InputStream in, final TransferStatus status) throws BackgroundException {
        return new Checksum(HashAlgorithm.sha1, this.digest("SHA-1",
                this.normalize(in, status), status));
    }
@Test
    public void testCompute() throws Exception {
        assertEquals("da39a3ee5e6b4b0d3255bfef95601890afd80709",
            new SHA1ChecksumCompute().compute(new NullInputStream(0), new TransferStatus()).hash);

    }