available = in.available();
TestCase.assertEquals(len2, available);
for(; i < len1 + len2; i++) {
TestCase.assertEquals((byte)i, (byte)in.read());
}
available = in.available();
TestCase.assertEquals(0, available);
// test available update until end of the block
final int len3 = (int) BLOCK_SIZE / 2;
AppendTestUtil.write(out, len1 + len2, len3);