Integration tests with Testcontainers

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Goal

Write integration tests using Testcontainers to spin up a real PostgreSQL container, run Flyway migrations, then execute repository and controller tests against it.

Prerequisites

• Docker and docker-compose

Dependency

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

Test configuration

Create src/test/resources/application-test.properties:

spring.datasource.url=jdbc:tc:postgresql:17-alpine:///itemsdb
spring.datasource.driver-class-name=org.testcontainers.jdbc.ContainerDatabaseDriver
spring.flyway.enabled=true
spring.jpa.hibernate.ddl-auto=validate

The tc: prefix in the URL tells Testcontainers to automatically start a PostgreSQL container.

Repository integration test

@SpringBootTest
@Testcontainers
class ItemRepositoryTest {

    @Autowired
    private ItemRepository repository;

    @Test
    void shouldSaveAndFind() {
        var item = new Item(null, "test", "description", false);
        var saved = repository.save(item);

        var found = repository.findById(saved.getId());
        assertThat(found).isPresent();
        assertThat(found.get().getTitle()).isEqualTo("test");
    }
}

Controller integration test

@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
@Testcontainers
class ItemControllerTest {

    @Autowired
    private TestRestTemplate rest;

    @Test
    void shouldListItems() {
        var response = rest.exchange(
            "/items", GET, null,
            new ParameterizedTypeReference<List<Item>>() {}
        );
        assertThat(response.getStatusCode()).isEqualTo(200);
    }
}

Run

./mvnw verify
# Testcontainers starts Postgres, runs Flyway migrat, executes tests, stops container
# All tests pass against real PostgreSQL

Checkpoint

./mvnw test
# Tests: 3, Passed: 3
# Testcontainers output: Container postgres:17-alpine started in 3.2s

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