@Test
public void retrievePostCallsNetwork() {

    Post post = mock(Post.class);
    String id = "id";
    when(network.retrievePost(id)).thenReturn(Observable.just(post));
    TestSubscriber<Post> ts = new TestSubscriber<>();
    tapglue.retrievePost(id).subscribe(ts);
    assertThat(ts.getOnNextEvents(), hasItems(post));
}