TestUtils.java

package com.example.guestbook;

import static com.example.guestbook.Persistence.getDatastore;

import com.google.cloud.datastore.Datastore;
import com.google.cloud.datastore.Key;
import com.google.cloud.datastore.Query;
import com.google.cloud.datastore.QueryResults;
import com.google.cloud.datastore.testing.LocalDatastoreHelper;
import com.google.common.collect.Lists;

import java.io.IOException;
import java.util.ArrayList;

public class TestUtils {
  static LocalDatastoreHelper datastore = LocalDatastoreHelper.create();

  public static void startDatastore() {
    try {
      datastore.start();
      Persistence.setDatastore(datastore.getOptions().getService());
    } catch (IOException | InterruptedException e) {
      throw new RuntimeException(e);
    }
  }

  public static void stopDatastore() {
    try {
      datastore.stop();
      Persistence.setDatastore(null);
    } catch (IOException | InterruptedException e) {
      throw new RuntimeException(e);
    }
  }

  public static void wipeDatastore() {
    Datastore datastore = getDatastore();
    QueryResults<Key> guestbooks = datastore.run(Query.newKeyQueryBuilder().setKind("Greeting")
        .build());
    ArrayList<Key> keys = Lists.newArrayList(guestbooks);

    if (!keys.isEmpty()) {
      datastore.delete(keys.toArray(new Key[keys.size()]));
    }
  }
}