@Test
public void updateCommentUpdatesOnService() {

    String postId = "postId";
    String commentId = "commentID";
    Comment comment = mock(Comment.class);
    when(service.updateComment(postId, commentId, comment)).thenReturn(Observable.just(comment));
    TestSubscriber<Comment> ts = new TestSubscriber<>();
    network.updateComment(postId, commentId, comment).subscribe(ts);
}