class Ecc25519Helper {

    public byte[] sign(byte[] message) {
        return signWithoutClamp(message, mKeyHolder.getPrivateKey(), mKeyHolder.getPublicKeySignature());
    }

}

class Ecc25519HelperTest {

    @Test
    public void ecc25519HelperSignIsSideEffectFreeOnPrivateKeyParameter() {

        // ensure that clamping of pk2 is side-effect free.
        // the .clone() calls are to make sure no other side effects affect the outcome.
        final byte[] pk1 = KeyHolder.createPrivateKey("hello".getBytes());
        final byte[] pk2 = pk1.clone();

        byte[] sig = new Ecc25519Helper().sign("message".getBytes(), pk2, new KeyHolder(pk1.clone()).getPublicKeySignature());

        assertArrayEquals(pk1, pk2);
    }

}