@Test
public void testWithCredentials() {

  Credentials credentials = Mockito.mock(Credentials.class);
  GrpcCallContext emptyContext = GrpcCallContext.createDefault();
  Truth.assertThat(emptyContext.getCallOptions().getCredentials()).isNull();
  GrpcCallContext context = emptyContext.withCredentials(credentials);
  Truth.assertThat(context.getCallOptions().getCredentials()).isNotNull();
}