### Question:
FingerprintMixer { long getAddend() { return mAddend; } FingerprintMixer(SecretKey secretKey, byte[] salt);  static final int SALT_LENGTH_BYTES; }### Answer:
@Test public void getAddend_withDifferentKey_returnsDifferentResult() throws Exception { int iterations = 100_000; HashSet<Long> returnedAddends = new HashSet<>(); byte[] salt = randomSalt(); for (int i = 0; i < iterations; i++) { FingerprintMixer fingerprintMixer = new FingerprintMixer(randomKey(), salt); long addend = fingerprintMixer.getAddend(); returnedAddends.add(addend); } assertThat(returnedAddends).containsNoDuplicates(); }