int read = is.read(buffer, 0, rs);
            if ( read < 0 ) {
                fail("Unexpected EOF");
            }

            byte verify[] = new byte[read];
            ReadWriteTest.randBytes(r, verify);
            byte actual[] = Arrays.copyOfRange(buffer, 0, read);

            assertArrayEquals("Data matches at offset " + p, actual, verify);

            p += read;
        }