@Override
    public void mark(int readAheadLimit) {
        mMark = mPosition;
    }
@Test
    void testMark() {
        UnsafeByteArrayInputStream stream = new UnsafeByteArrayInputStream("abc".getBytes(), 1);
        assertThat(stream.markSupported(), is(true));

        stream.mark(2);
        stream.read();
        assertThat(stream.position(), is(2));
        stream.reset();
        assertThat(stream.position(), is(1));
    }