Code samples for a blog post at http://www.objectify.be/wordpress/2017/03/28/database-testing-with-testcontainers/

AbstractUserDaoTest.java

package be.objectify.tcexample;

import org.junit.Test;
import static org.assertj.core.api.Assertions.assertThat;

public abstract AbstractUserDaoTest {
    @Test
    public void testFoo() {
        assertThat(dao().something()).isEqualTo(whatever);
    }

    // many, many more tests

    public abstract UserDao dao();
}

DbTestSupport.java

package be.objectify.tcexample.db;

import com.google.common.collect.ImmutableMap;
import org.testcontainers.containers.PostgreSQLContainer;
import play.db.Database;
import play.db.Databases;
import play.db.evolutions.Evolutions;

public interface DbTestSupport {

    default Database create(final PostgreSQLContainer postgres) throws Exception {
        final Database database = Databases.createFrom("default",
                                                       postgres.getDriverClassName(),
                                                       postgres.getJdbcUrl(),
                                                       ImmutableMap.of("username", postgres.getUsername(),
                                                                       "password", postgres.getPassword()));
        Evolutions.applyEvolutions(database);
        return database;
    }

    default void destroy(final Database database) {
        Evolutions.cleanupEvolutions(database);
        database.shutdown();
    }
}

FooDaoTest.java

public class FooDaoTest {
    @Rule
    public PostgreSQLContainer postgres = new PostgreSQLContainer();

    @Before
    public void setUp() {
        // populate database
        // postgres.getDriverClassName()
        // postgres.getJdbcUrl()
        // postgres.getUsername()
        // postgres.getPassword()
    }
}

JooqUserDaoTest.java

package be.objectify.tcexample.db;

import be.objectify.tcexample.AbstractUserDaoTest;
import be.objectify.tcexample.UserDao;
import org.junit.After;
import org.junit.Before;
import org.junit.Rule;
import org.testcontainers.containers.PostgreSQLContainer;
import play.db.Database;

public class JooqUserDaoTest extends AbstractUserDaoTest implements DbTestSupport,
                                                                    TestData {

    @Rule
    public PostgreSQLContainer postgres = new PostgreSQLContainer();
    
    private Database database;
    
    @Before
    public void setup() throws Exception {
        // the database has all evolutions applied
        database = create(postgres); 
        // load some test data
        loadTestData(database); 
    }

    @After
    public void tearDown() {
        destroy(database);
    }

    @Override
    public UserDao dao() {
        return new JooqUserDao(database);
    }
}

TestData.java

package be.objectify.tcexample.db;
    
import org.jooq.impl.DSL;
import play.db.Database;
    
import java.sql.Connection;
import java.sql.Timestamp;
import java.time.Instant;
    
import static be.objectify.tcexample.db.jooq.generated.Tables.ACCOUNT;
    
public interface TestData {
    default void loadTestData(Database database) {
        database.withConnection((Connection conn) -> {
            DSL.using(conn)
               .insertInto(ACCOUNT,
                           ACCOUNT.ID,
                           ACCOUNT.KEY,
                           ACCOUNT.CREATED_ON)
               .values(1,
                       "test-account-a",
                       Timestamp.from(Instant.now()))
               .execute();
            DSL.using(conn)
               .insertInto(ACCOUNT,
                           ACCOUNT.ID,
                           ACCOUNT.KEY,
                           ACCOUNT.CREATED_ON)
               .values(2,
                       "test-account-b",
                       Timestamp.from(Instant.now()))
               .execute();
        });
    }
}