throws IOException {
final int valueLen = DEFAULT_INTERNAL_BUFFER_SIZE + 5*1024;
InputStream is = getStream(valueLen);
is.mark(valueLen - 1024);
// Obtain a header generator to compare with.
ClobStreamHeaderGenerator hdrGen = new ClobStreamHeaderGenerator(false);
byte[] hdrTmp = new byte[100];
int headerLen = hdrGen.generateInto(hdrTmp, 0, valueLen);
byte[] hdr1 = new byte[headerLen];
System.arraycopy(hdrTmp, 0, hdr1, 0, headerLen);
byte[] hdr2 = new byte[headerLen];
// Get the first bytes from the stream being tested.
assertEquals(headerLen, is.read(hdr2));