Testcontainers

Testcontainers - Quick Reference

Deep Knowledge: Use mcp__documentation__fetch_docs with technology: testcontainers for comprehensive documentation.

When NOT to Use This Skill

• Unit Tests - Use junit with Mockito for fast isolated tests
• REST API Tests Only - Use rest-assured without containers if API is mocked
• Environments Without Docker - Use H2 or embedded databases
• CI with Limited Resources - Containers may be too heavy, use mocks
• Non-Java Projects - Check language-specific Testcontainers libraries

Setup Base

Maven Dependencies

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-testcontainers</artifactId>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.testcontainers</groupId>
    <artifactId>junit-jupiter</artifactId>
    <scope>test</scope>
</dependency>
<!-- Database specific -->
<dependency>
    <groupId>org.testcontainers</groupId>
    <artifactId>postgresql</artifactId>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.testcontainers</groupId>
    <artifactId>mongodb</artifactId>
    <scope>test</scope>
</dependency>

Gradle Dependencies

testImplementation("org.springframework.boot:spring-boot-testcontainers")
testImplementation("org.testcontainers:junit-jupiter")
testImplementation("org.testcontainers:postgresql")
testImplementation("org.testcontainers:mongodb")

@ServiceConnection (Spring Boot 3.1+)

Pattern Raccomandato

@SpringBootTest
@Testcontainers
class MyIntegrationTest {

    @Container
    @ServiceConnection
    static PostgreSQLContainer<?> postgres =
        new PostgreSQLContainer<>("postgres:16-alpine");

    @Test
    void testWithDatabase() {
        // Connection auto-configured
    }
}

Container Supportati

GenericContainer con @ServiceConnection

@Container
@ServiceConnection(name = "redis")
static GenericContainer<?> redis =
    new GenericContainer<>("redis:7-alpine")
        .withExposedPorts(6379);

Lifecycle Management

Static Container (Shared across tests - RECOMMENDED)

@Testcontainers
class SharedContainerTest {

    @Container
    static PostgreSQLContainer<?> postgres =
        new PostgreSQLContainer<>("postgres:16-alpine");

    @Test
    void test1() { /* same container */ }

    @Test
    void test2() { /* same container */ }
}

Spring Bean Container (Best lifecycle control)

@TestConfiguration(proxyBeanMethods = false)
class TestContainersConfig {

    @Bean
    @ServiceConnection
    PostgreSQLContainer<?> postgresContainer() {
        return new PostgreSQLContainer<>("postgres:16-alpine");
    }
}

@SpringBootTest
@Import(TestContainersConfig.class)
class ManagedContainerTest {
    // Container lifecycle managed by Spring
    // Started before beans, stopped after beans
}

Container Reuse (Development)

static PostgreSQLContainer<?> postgres =
    new PostgreSQLContainer<>("postgres:16-alpine")
        .withReuse(true);

Richiede in ~/.testcontainers.properties:

testcontainers.reuse.enable=true

Database Containers

PostgreSQL

@Container
@ServiceConnection
static PostgreSQLContainer<?> postgres =
    new PostgreSQLContainer<>("postgres:16-alpine")
        .withDatabaseName("testdb")
        .withUsername("test")
        .withPassword("test")
        .withInitScript("init.sql");

MongoDB

@Container
@ServiceConnection
static MongoDBContainer mongo =
    new MongoDBContainer("mongo:7.0")
        .withSharding();

MySQL

@Container
@ServiceConnection
static MySQLContainer<?> mysql =
    new MySQLContainer<>("mysql:8.0")
        .withDatabaseName("testdb")
        .withUsername("test")
        .withPassword("test");

Messaging Containers

Kafka

@Container
@ServiceConnection
static KafkaContainer kafka =
    new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:7.5.0"))
        .withKraft();

RabbitMQ

@Container
@ServiceConnection
static RabbitMQContainer rabbitmq =
    new RabbitMQContainer("rabbitmq:3.12-management")
        .withExposedPorts(5672, 15672);

Redis

@Container
@ServiceConnection
static GenericContainer<?> redis =
    new GenericContainer<>("redis:7-alpine")
        .withExposedPorts(6379);

Messaging Container Test Patterns

Dedicated skills: For comprehensive messaging test coverage, see messaging-testing-kafka, messaging-testing-rabbitmq, and messaging-testing.

Kafka: Produce → Consume → Assert

@SpringBootTest
@Testcontainers
class KafkaProduceConsumeTest {

    @Container
    @ServiceConnection
    static KafkaContainer kafka = new KafkaContainer(
        DockerImageName.parse("apache/kafka-native:3.8.0"));

    @Autowired
    private KafkaTemplate<String, OrderEvent> kafkaTemplate;

    @Autowired
    private OrderRepository orderRepository;

    @Test
    void shouldProcessOrderViaKafka() throws Exception {
        kafkaTemplate.send("orders", "key-1",
            new OrderEvent("123", "CREATED")).get(10, TimeUnit.SECONDS);

        await().atMost(Duration.ofSeconds(10))
            .untilAsserted(() ->
                assertThat(orderRepository.findById("123")).isPresent());
    }
}

RabbitMQ: Send → Listen → Assert

@SpringBootTest
@Testcontainers
class RabbitProduceConsumeTest {

    @Container
    @ServiceConnection
    static RabbitMQContainer rabbit = new RabbitMQContainer("rabbitmq:3.13-management");

    @Autowired
    private RabbitTemplate rabbitTemplate;

    @Autowired
    private OrderRepository orderRepository;

    @Test
    void shouldProcessOrderViaRabbit() {
        rabbitTemplate.convertAndSend("orders.exchange", "orders.created",
            new OrderEvent("456", "CREATED"));

        await().atMost(Duration.ofSeconds(10))
            .untilAsserted(() ->
                assertThat(orderRepository.findById("456")).isPresent());
    }
}

Redis Pub/Sub: Publish → Subscribe → Assert

@SpringBootTest
@Testcontainers
class RedisPubSubTest {

    @Container
    @ServiceConnection(name = "redis")
    static GenericContainer<?> redis =
        new GenericContainer<>("redis:7-alpine").withExposedPorts(6379);

    @Autowired
    private StringRedisTemplate redisTemplate;

    @Test
    void shouldPublishAndReceiveMessage() throws Exception {
        CountDownLatch latch = new CountDownLatch(1);
        List<String> received = new CopyOnWriteArrayList<>();

        RedisMessageListenerContainer container = new RedisMessageListenerContainer();
        container.setConnectionFactory(redisTemplate.getConnectionFactory());
        container.addMessageListener((message, pattern) -> {
            received.add(new String(message.getBody()));
            latch.countDown();
        }, new ChannelTopic("orders"));
        container.afterPropertiesSet();
        container.start();

        redisTemplate.convertAndSend("orders", "{\"orderId\":\"789\"}");

        assertThat(latch.await(5, TimeUnit.SECONDS)).isTrue();
        assertThat(received.get(0)).contains("789");
        container.stop();
    }
}

Legacy Pattern (@DynamicPropertySource)

@Testcontainers
@SpringBootTest
class LegacyTest {

    @Container
    static PostgreSQLContainer<?> postgres =
        new PostgreSQLContainer<>("postgres:16");

    @DynamicPropertySource
    static void configureProperties(DynamicPropertyRegistry registry) {
        registry.add("spring.datasource.url", postgres::getJdbcUrl);
        registry.add("spring.datasource.username", postgres::getUsername);
        registry.add("spring.datasource.password", postgres::getPassword);
    }
}

Network & Compose

Container Network

@Testcontainers
class NetworkTest {

    static Network network = Network.newNetwork();

    @Container
    static PostgreSQLContainer<?> postgres =
        new PostgreSQLContainer<>("postgres:16")
            .withNetwork(network)
            .withNetworkAliases("postgres");

    @Container
    static GenericContainer<?> app =
        new GenericContainer<>("myapp:latest")
            .withNetwork(network)
            .dependsOn(postgres)
            .withEnv("DATABASE_HOST", "postgres");
}

Docker Compose

@Testcontainers
class ComposeTest {

    @Container
    static DockerComposeContainer<?> compose =
        new DockerComposeContainer<>(new File("docker-compose-test.yml"))
            .withExposedService("postgres", 5432)
            .withExposedService("redis", 6379);

    @Test
    void test() {
        String host = compose.getServiceHost("postgres", 5432);
        int port = compose.getServicePort("postgres", 5432);
    }
}

Wait Strategies

new GenericContainer<>("custom-image")
    .waitingFor(Wait.forHttp("/health").forStatusCode(200))
    .waitingFor(Wait.forLogMessage(".*Started.*", 1))
    .waitingFor(Wait.forListeningPort())
    .withStartupTimeout(Duration.ofMinutes(2));

Best Practices

Common Issues

Container not starting

// Check Docker is running
// Check image exists
// Increase startup timeout
.withStartupTimeout(Duration.ofMinutes(5))

Port conflicts

// Always use exposed port mapping
container.getMappedPort(5432)
// Never hardcode ports

Slow tests

// Enable reuse
.withReuse(true)
// Use lighter images (-alpine)
new PostgreSQLContainer<>("postgres:16-alpine")

Anti-Patterns

Quick Troubleshooting

Reference Documentation

• Testcontainers Official Docs
• Spring Boot Testcontainers