ok-testing-reloaded-medium

ContentTypeRoute.java

public class ContentTypeRoute implements Route {

  private final String contentType;
  private final Route delegate;
  private final Optional<ResponseTransformer> responseTransformer;

  private ContentTypeRoute(String contentType, Route delegate,
                           ResponseTransformer responseTransformer) {
    this.contentType = contentType;
    this.delegate = delegate;
    this.responseTransformer = Optional.ofNullable(responseTransformer);
  }

  @Override
  public Object handle(Request request, Response response) throws Exception {
    final Object result = delegateAndTransform(request, response);

    response.header("Content-Type", contentType);

    return result;
  }

  private Object delegateAndTransform(Request request, Response response)
    throws Exception {
    final Object data = delegate.handle(request, response);

    if (responseTransformer.isPresent()) {
      return responseTransformer.get().render(data);
    }

    return data;
  }

  public static Route create(Route delegate, String contentType) {
    return create(delegate, contentType, null);
  }

  public static Route create(Route delegate, String contentType,
                             ResponseTransformer responseTransformer) {
    return new ContentTypeRoute(contentType, delegate, responseTransformer);
  }
}

MoshiResponseTransformer.java

public class MoshiResponseTransformer<T> implements ResponseTransformer {

  private final Moshi moshi;
  private final Class<T> type;

  private MoshiResponseTransformer(Moshi moshi, Class<T> type) {
    this.moshi = moshi;
    this.type = type;
  }

  @SuppressWarnings("unchecked")
  @Override
  public String render(Object model) throws Exception {
    return moshi.adapter(type).toJson((T) model);
  }

  public static ResponseTransformer create(Class<?> type) {
    return create(new Moshi.Builder().build(), type);
  }

  public static ResponseTransformer create(Moshi moshi, Class<?> type) {
    return new MoshiResponseTransformer<>(moshi, type);
  }
}

RetweetsIdRoute.java

public class RetweetsIdRoute implements Route {

  @Override
  public Object handle(Request request, Response response) throws Exception {
    final String idParam = request.params(":id");
    final String count = request.queryParams("count");

    return fetchTweets(
      Long.valueOf(idParam),
      Integer.valueOf(count != null && count.length() > 0 ? count : "100")
    );
  }

  private List<Tweet> fetchTweets(long id, int count) {
    final List<Tweet> tweets = new ArrayList<Tweet>(count);
    for (int i = 0; i < count; i++) {
      final Tweet tweet = new Tweet();
      tweet.id = id + i;
      tweet.text = String.format("Retweet #%s of %s for %s", i, count, id);
      tweet.favorited = i % 2 == 0;

      tweets.add(tweet);
    }

    return tweets;
  }

  public static Route create() {
    return new RetweetsIdRoute();
  }
}

TwitterApp.java

import static spark.Spark.get;

public class TwitterApp implements SparkApplication {

  @Override
  public void init() {

    get(
      "statuses/retweets/:id",
      "*/*",
      ContentTypeRoute.create(
        RetweetsIdRoute.create(),
        "application/json",
        MoshiResponseTransformer.create(
          new Moshi.Builder()
            .add(Date.class,
              new DateJsonAdapter("EEE MMM dd kk:mm:ss z yyyy").nullSafe())
            .build(),
          List.class
        )
      )
    );
  }
}