@Test
public void sign_shouldReturnSameSignOnTwoIdenticalCalls() throws NoSuchAlgorithmException, InvalidKeyException, SignatureException {

    PrivateKey privateKey = generatePrivateKey();
    String signA = CryptoBase.sign("my_message", privateKey);
    String signB = CryptoBase.sign("my_message", privateKey);
    assertThat(signA)
            .isNotEmpty()
            .isEqualTo(signB);
}