InputStream s = new ByteArrayInputStream(new byte[] { (byte) 0x80 });
        int length = ASN1Util.readLength(s, 100, false);
        assertEquals(-1, length);
    }

    @Test
    void testReadLength_EOF() {
        // EOF when length expected
        InputStream s = new ByteArrayInputStream(new byte[] {});
        assertThrows(EOFException.class, () -> {
            ASN1Util.readLength(s, 100, false);
        });