assertNotNull(result);
    }

    @Test
    void testEngineGetDigestLength() {
        // Test engineGetDigestLength()
        HMACT64 hmac = new HMACT64(TEST_KEY);
        // MD5 digest length is 16 bytes
        assertEquals(16, hmac.engineGetDigestLength());
    }

    @Test
    void testEngineDigest() {
        // Test engineDigest()
        HMACT64 hmac = new HMACT64(TEST_KEY);

        try {
            return this.md5.digest(buf, offset, len);
        } catch (final Exception ex) {
            throw new IllegalStateException();
        }
    }

    @Override
    protected int engineGetDigestLength() {
        return this.md5.getDigestLength();
    }

    @Override
    protected void engineReset() {
        this.md5.reset();
        this.md5.update(this.ipad);
    }

    @Override

        try {
            return md5.digest(buf, offset, len);
        } catch (final Exception ex) {
            throw new IllegalStateException();
        }
    }

    @Override
    protected int engineGetDigestLength() {
        return md5.getDigestLength();
    }

    @Override
    protected void engineReset() {
        md5.reset();
        md5.update(ipad);
    }

    @Override