java - 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 1

Since Spring Boot version 1.3 there is an EmbeddedMongoAutoConfiguration class which comes out of the box. This means that you don't have to create a configuration file at all and if you want to change things you still can.

Auto-configuration for Embedded MongoDB has been added. A dependency on de.flapdoodle.embed:de.flapdoodle.embed.mongo is all that’s necessary to get started. Configuration, such as the version of Mongo to use, can be controlled via application.properties. Please see the documentation for further information. (Spring Boot Release Notes)

The most basic and important configuration that has to be added to the application.properties files is
spring.data.mongodb.port=0 (0 means that it will be selected randomly from the free ones)

for more details check: Spring Boot Docs MongoDb