@Test
    public void testResetWithoutMark() throws IOException {
        final int tailSize = 75;
        final int count = 128;
        TailStream stream = new TailStream(generateStream(0, count), tailSize);
        stream.reset();
        byte[] buf = new byte[count];
        stream.read(buf);
        assertEquals(generateText(count - tailSize, tailSize),
                new String(stream.getTail(), UTF_8), "Wrong buffer");
        stream.close();
    }
Tests whether a reset() operation without a mark is simply ignored.
tika-core/src/test/java/org/apache/tika/io/TailStreamTest.java