// Simple tag 5
        InputStream s = new ByteArrayInputStream(new byte[] {});
        int tagNo = ASN1Util.readTagNumber(s, 0x05);
        assertEquals(5, tagNo);
    }

    @Test
    void testReadTagNumber_HighTag() throws IOException {
        // High tag number (31)
        InputStream s = new ByteArrayInputStream(new byte[] { 0x1F });
        int tagNo = ASN1Util.readTagNumber(s, 0x1F);
        assertEquals(31, tagNo);