@Test
public void getPrimitive_works() throws Exception {

  AesCmacPrfKeyManager manager = new AesCmacPrfKeyManager();
  AesCmacPrfKey validKey = manager.keyFactory().createKey(makeAesCmacPrfKeyFormat(32));
  PrfSet managerPrf = manager.getPrimitive(validKey, PrfSet.class);
  Prf directPrf = new PrfAesCmac(validKey.getKeyValue().toByteArray());
  byte[] message = Random.randBytes(50);
  assertThat(managerPrf.computePrimary(message, 16)).isEqualTo(directPrf.compute(message, 16));
}