How to use

getRandomInstance

method

in

com.nike.wingtips.TraceAndSpanIdGenerator

@Test
public void getRandomInstance_should_default_to_normal_random_if_desired_algorithm_is_not_available() {
  Random randomGenerator = TraceAndSpanIdGenerator.getRandomInstance("QuantumDoohickey");
  assertThat(randomGenerator).isNotNull();
  assertThat(randomGenerator).isNotInstanceOf(SecureRandom.class);
}

@Test
public void getRandomInstance_should_return_requested_instance_if_available() {
  // given: all available SecureRandom algorithm providers
  Provider[] availableProviders = Security.getProviders();
  assertThat(availableProviders).isNotNull();
  assertThat(availableProviders.length).isGreaterThanOrEqualTo(1);
  // Ignore some algorithms because they fail on OSX if you're not an admin.
  // We don't care that *all* algorithms are available at all times on all platforms, just that the code does what it's supposed to do.
  List<String> excludedAlgorithms = Collections.singletonList("NativePRNGNonBlocking");
  Set<String> availableSecureRandomAlgorithms = new HashSet<>();
  for (Provider provider : availableProviders) {
    Set<Provider.Service> services = provider.getServices();
    for (Provider.Service service : services) {
      String type = service.getType();
      if ("SecureRandom".equals(type) && !excludedAlgorithms.contains(service.getAlgorithm()))
        availableSecureRandomAlgorithms.add(service.getAlgorithm());
    }
  }
  assertThat(availableSecureRandomAlgorithms).isNotEmpty();
  for (String algorithm : availableSecureRandomAlgorithms) {
    // when: we ask getRandomInstance for the algorithm
    Random randomGenerator = TraceAndSpanIdGenerator.getRandomInstance(algorithm);
    // then: we get back a valid SecureRandom that uses the requested algorithm
    assertThat(randomGenerator).isNotNull();
    assertThat(randomGenerator).isInstanceOf(SecureRandom.class);
    //noinspection ConstantConditions
    assertThat(((SecureRandom)randomGenerator).getAlgorithm()).isEqualTo(algorithm);
  }
}