InputStream s = new ByteArrayInputStream(new byte[] { 0x1E });
        assertThrows(IOException.class, () -> {
            ASN1Util.readTagNumber(s, 0x1F);
        });
    }

    @Test
    void testReadTagNumber_EOF() {
        // EOF inside tag value
        InputStream s = new ByteArrayInputStream(new byte[] {});
        assertThrows(EOFException.class, () -> {
            ASN1Util.readTagNumber(s, 0x1F);
        });