ASN1Util.readUnparsedTagged(2, 10, ais);
        }, "Should throw IOException for unexpected tag");
    }

    // --- readTagNumber ---

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