title: Cannot import android.arch.persistence.room.testing.MigrationTestHelper
body: <p>I have read <a href="https://developer.android.com/topic/libraries/architecture/room.html#db-migration" rel="noreferrer">Room Persistence Library</a>. I also clone <a href="https://github.com/googlesamples/android-architecture-components/tree/master/GithubBrowserSample" rel="noreferrer">android-architecture-components</a> then I try to add Mirgration test. However, I cannot import </p>
  
  <pre><code>import android.arch.persistence.room.testing.MigrationTestHelper;
  </code></pre>
  
  <p>I also use latest lib version which is.</p>
  
  <pre><code>android.arch.core:core-testing:1.0.0-alpha3
  </code></pre>
  
  <p>Here is the code for MigrationTest</p>
  
  <pre><code>import android.arch.persistence.db.SupportSQLiteDatabase;
  import android.arch.persistence.db.framework.FrameworkSQLiteOpenHelperFactory;
  import android.support.test.InstrumentationRegistry;
  import android.support.test.runner.AndroidJUnit4;
  
  import org.junit.Rule;
  import org.junit.Test;
  import org.junit.runner.RunWith;
  
  import java.io.IOException;
  import android.arch.persistence.room.testing.MigrationTestHelper;
  
  @RunWith(AndroidJUnit4.class)
  public class MigrationTest {
      private static final String TEST_DB = "migration-test";
  
      @Rule
      public MigrationTestHelper helper;
  
      public MigrationTest() {
          helper = new MigrationTestHelper(InstrumentationRegistry.getInstrumentation(),
                  MigrationDb.class.getCanonicalName(),
                  new FrameworkSQLiteOpenHelperFactory());
      }
  
      @Test
      public void migrate1To2() throws IOException {
          SupportSQLiteDatabase db = helper.createDatabase(TEST_DB, 1);
  
          // db has schema version 1. insert some data using SQL queries.
          // You cannot use DAO classes because they expect the latest schema.
          //db.execSQL(...);
  
          // Prepare for the next version.
          db.close();
  
          // Re-open the database with version 2 and provide
          // MIGRATION_1_2 as the migration process.
          db = helper.runMigrationsAndValidate(TEST_DB, 2, true, MIGRATION_1_2);
  
          // MigrationTestHelper automatically verifies the schema changes,
          // but you need to validate that the data was migrated properly.
      }
  }
  </code></pre>