How do you configure Embedded MongDB for integration testing in a Spring Boot application?

Question

I have a fairly simple Spring Boot application which exposes a small REST API and retrieves data from an instance of MongoDB. Queries to the MongoDB instance go through a Spring Data based repository. Some key bits of code below.

// Main application class
@EnableAutoConfiguration(exclude={MongoAutoConfiguration.class, MongoDataAutoConfiguration.class})
@ComponentScan
@Import(MongoConfig.class)
public class ProductApplication {
    public static void main(String[] args) {
        SpringApplication.run(ProductApplication.class, args);
    }
}



// Product repository with Spring data
public interface ProductRepository extends MongoRepository<Product, String> {

    Page<Product> findAll(Pageable pageable);

    Optional<Product> findByLineNumber(String lineNumber);
}



// Configuration for "live" connections
@Configuration
public class MongoConfig {

    @Value("${product.mongo.host}")
    private String mongoHost;

    @Value("${product.mongo.port}")
    private String mongoPort;

    @Value("${product.mongo.database}")
    private String mongoDatabase;

    @Bean(name="mongoClient")
    public MongoClient mongoClient() throws IOException {
        return new MongoClient(mongoHost, Integer.parseInt(mongoPort));
    }

    @Autowired
    @Bean(name="mongoDbFactory")
    public MongoDbFactory mongoDbFactory(MongoClient mongoClient) {
        return new SimpleMongoDbFactory(mongoClient, mongoDatabase);
    }

    @Autowired
    @Bean(name="mongoTemplate")
    public MongoTemplate mongoTemplate(MongoClient mongoClient) {
        return new MongoTemplate(mongoClient, mongoDatabase);
    }
}



@Configuration
@EnableMongoRepositories
public class EmbeddedMongoConfig {

    private static final String DB_NAME = "integrationTest";
    private static final int DB_PORT = 12345;
    private static final String DB_HOST = "localhost";
    private static final String DB_COLLECTION = "products";

    private MongodExecutable mongodExecutable = null;

    @Bean(name="mongoClient")
    public MongoClient mongoClient() throws IOException {
        // Lots of calls here to de.flapdoodle.embed.mongo code base to 
        // create an embedded db and insert some JSON data
    }

    @Autowired
    @Bean(name="mongoDbFactory")
    public MongoDbFactory mongoDbFactory(MongoClient mongoClient) {
        return new SimpleMongoDbFactory(mongoClient, DB_NAME);
    }

    @Autowired
    @Bean(name="mongoTemplate")
    public MongoTemplate mongoTemplate(MongoClient mongoClient) {
        return new MongoTemplate(mongoClient, DB_NAME);
    }

    @PreDestroy
    public void shutdownEmbeddedMongoDB() {
        if (this.mongodExecutable != null) {
            this.mongodExecutable.stop();
        }
    }
}



@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = TestProductApplication.class)
@IntegrationTest
@WebAppConfiguration
public class WtrProductApplicationTests {

    @Test
    public void contextLoads() {
        // Tests empty for now
    }

}



@EnableAutoConfiguration(exclude={MongoAutoConfiguration.class, MongoDataAutoConfiguration.class})
@ComponentScan
@Import(EmbeddedMongoConfig.class)
public class TestProductApplication {

    public static void main(String[] args) {
        SpringApplication.run(TestProductApplication.class, args);
    }
}

So the idea here is to have the integration tests (empty at the moment) connect to the embedded mongo instance and not the "live" one. However, it doesn't work. I can see the tests connecting to the "live" instance of Mongo, and if I shut that down the build simply fails as it is still attempting to connect to the live instance of Mongo. Does anyone know why this is? How do I get the tests to connect to the embedded instance?

Answer

EDIT : see magiccrafter's answer for Spring Boot 1.3+, using EmbeddedMongoAutoConfiguration.

If you can't use it for any reason, keep reading.

Test class:

    @RunWith(SpringJUnit4ClassRunner.class)
    @SpringApplicationConfiguration(classes = {
        Application.class, 
        TestMongoConfig.class // <--- Don't forget THIS
    })
    public class GameRepositoryTest {

        @Autowired
        private GameRepository gameRepository;

        @Test
        public void shouldCreateGame() {
            Game game = new Game(null, "Far Cry 3");
            Game gameCreated = gameRepository.save(game);
            assertEquals(gameCreated.getGameId(), gameCreated.getGameId());
            assertEquals(game.getName(), gameCreated.getName());
        }

    } 

Simple MongoDB repository:

public interface GameRepository extends MongoRepository<Game, String>     {

    Game findByName(String name);
}

MongoDB test configuration:

import com.mongodb.Mongo;
import com.mongodb.MongoClientOptions;
import de.flapdoodle.embed.mongo.MongodExecutable;
import de.flapdoodle.embed.mongo.MongodProcess;
import de.flapdoodle.embed.mongo.MongodStarter;
import de.flapdoodle.embed.mongo.config.IMongodConfig;
import de.flapdoodle.embed.mongo.config.MongodConfigBuilder;
import de.flapdoodle.embed.mongo.config.Net;
import de.flapdoodle.embed.mongo.distribution.Version;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.mongo.MongoProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.io.IOException;

@Configuration
public class TestMongoConfig {

    @Autowired
    private MongoProperties properties;

    @Autowired(required = false)
    private MongoClientOptions options;

    @Bean(destroyMethod = "close")
    public Mongo mongo(MongodProcess mongodProcess) throws IOException {
        Net net = mongodProcess.getConfig().net();
        properties.setHost(net.getServerAddress().getHostName());
        properties.setPort(net.getPort());
        return properties.createMongoClient(this.options);
    }

    @Bean(destroyMethod = "stop")
    public MongodProcess mongodProcess(MongodExecutable mongodExecutable) throws IOException {
        return mongodExecutable.start();
    }

    @Bean(destroyMethod = "stop")
    public MongodExecutable mongodExecutable(MongodStarter mongodStarter, IMongodConfig iMongodConfig) throws IOException {
        return mongodStarter.prepare(iMongodConfig);
    }

    @Bean
    public IMongodConfig mongodConfig() throws IOException {
        return new MongodConfigBuilder().version(Version.Main.PRODUCTION).build();
    }

    @Bean
    public MongodStarter mongodStarter() {
        return MongodStarter.getDefaultInstance();
    }

}

pom.xml

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb</artifactId>
        </dependency>
        <dependency>
            <groupId>de.flapdoodle.embed</groupId>
            <artifactId>de.flapdoodle.embed.mongo</artifactId>
            <version>1.48.0</version>
            <scope>test</scope>
        </dependency>