JUnit 5 extension annotations
The Testcontainers library provides a JUnit 5 extension that simplifies
starting and stopping containers using annotations. To use it, add the
org.testcontainers:testcontainers-junit-jupiter test dependency.
package com.testcontainers.demo;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.util.List;
import java.util.Optional;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.testcontainers.postgresql.PostgreSQLContainer;
import org.testcontainers.junit.jupiter.Container;
import org.testcontainers.junit.jupiter.Testcontainers;
@Testcontainers
class CustomerServiceWithJUnit5ExtensionTest {
@Container
static PostgreSQLContainer postgres = new PostgreSQLContainer(
"postgres:16-alpine"
);
CustomerService customerService;
@BeforeEach
void setUp() {
customerService =
new CustomerService(
postgres.getJdbcUrl(),
postgres.getUsername(),
postgres.getPassword()
);
customerService.deleteAllCustomers();
}
@Test
void shouldCreateCustomer() {
customerService.createCustomer(new Customer(1L, "George"));
Optional<Customer> customer = customerService.getCustomer(1L);
assertTrue(customer.isPresent());
assertEquals(1L, customer.get().id());
assertEquals("George", customer.get().name());
}
@Test
void shouldGetCustomers() {
customerService.createCustomer(new Customer(1L, "George"));
customerService.createCustomer(new Customer(2L, "John"));
List<Customer> customers = customerService.getAllCustomers();
assertEquals(2, customers.size());
}
}Instead of manually starting and stopping the container in @BeforeAll and
@AfterAll, the @Testcontainers annotation on the class and the
@Container annotation on the field handle it automatically:
- The extension finds all
@Container-annotated fields. - Static fields start once before all tests and stop after all tests.
- Instance fields start before each test and stop after each test (not recommended — it's resource-intensive).