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Write tests with Testcontainers

Table of contents

Before writing the tests, create an SQL script to seed test data at src/test/resources/test-data.sql:

DELETE FROM comments;
DELETE FROM posts;
DELETE FROM users;

INSERT INTO users(id, name, email) VALUES
(1, 'Siva', 'siva@gmail.com'),
(2, 'Oleg', 'oleg@gmail.com');

INSERT INTO posts(id, title, content, created_by, created_at) VALUES
(1, 'Post 1 Title', 'Post 1 content', 1, CURRENT_TIMESTAMP),
(2, 'Post 2 Title', 'Post 2 content', 2, CURRENT_TIMESTAMP);

INSERT INTO comments(id, name, content, post_id, created_at) VALUES
(1, 'Ron', 'Comment 1', 1, CURRENT_TIMESTAMP),
(2, 'James', 'Comment 2', 1, CURRENT_TIMESTAMP),
(3, 'Robert', 'Comment 3', 2, CURRENT_TIMESTAMP);

Test with the @JooqTest slice

The @JooqTest annotation loads only the persistence layer components and auto-configures jOOQ's DSLContext. Use the Testcontainers special JDBC URL to start a Postgres container.

Create UserRepositoryJooqTest.java:

package com.testcontainers.demo.domain;

import static org.assertj.core.api.Assertions.assertThat;

import org.jooq.DSLContext;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.jooq.JooqTest;
import org.springframework.test.context.jdbc.Sql;

@JooqTest(
  properties = {
    "spring.test.database.replace=none",
    "spring.datasource.url=jdbc:tc:postgresql:16-alpine:///db",
  }
)
@Sql("/test-data.sql")
class UserRepositoryJooqTest {

  @Autowired
  DSLContext dsl;

  UserRepository repository;

  @BeforeEach
  void setUp() {
    this.repository = new UserRepository(dsl);
  }

  @Test
  void shouldCreateUserSuccessfully() {
    User user = new User(null, "John", "john@gmail.com");

    User savedUser = repository.createUser(user);

    assertThat(savedUser.id()).isNotNull();
    assertThat(savedUser.name()).isEqualTo("John");
    assertThat(savedUser.email()).isEqualTo("john@gmail.com");
  }

  @Test
  void shouldGetUserByEmail() {
    User user = repository.getUserByEmail("siva@gmail.com").orElseThrow();

    assertThat(user.id()).isEqualTo(1L);
    assertThat(user.name()).isEqualTo("Siva");
    assertThat(user.email()).isEqualTo("siva@gmail.com");
  }
}

Here's what the test does:

  • @JooqTest loads only the persistence layer and auto-configures DSLContext.
  • The Testcontainers special JDBC URL (jdbc:tc:postgresql:16-alpine:///db) starts a PostgreSQL container automatically.
  • Because flyway-core is on the classpath, Spring Boot runs the Flyway migrations from src/main/resources/db/migration on startup.
  • @Sql("/test-data.sql") loads the test data before each test.
  • The UserRepository is instantiated manually with the injected DSLContext.

Integration test with @SpringBootTest

For a full integration test, use @SpringBootTest with the Testcontainers @ServiceConnection support introduced in Spring Boot 3.1.

Create UserRepositoryTest.java:

package com.testcontainers.demo.domain;

import static org.assertj.core.api.Assertions.assertThat;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.testcontainers.service.connection.ServiceConnection;
import org.springframework.test.context.jdbc.Sql;
import org.testcontainers.postgresql.PostgreSQLContainer;
import org.testcontainers.junit.jupiter.Container;
import org.testcontainers.junit.jupiter.Testcontainers;

@SpringBootTest
@Sql("/test-data.sql")
@Testcontainers
class UserRepositoryTest {

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

  @Autowired
  UserRepository repository;

  @Test
  void shouldCreateUserSuccessfully() {
    User user = new User(null, "John", "john@gmail.com");

    User savedUser = repository.createUser(user);

    assertThat(savedUser.id()).isNotNull();
    assertThat(savedUser.name()).isEqualTo("John");
    assertThat(savedUser.email()).isEqualTo("john@gmail.com");
  }

  @Test
  void shouldGetUserByEmail() {
    User user = repository.getUserByEmail("siva@gmail.com").orElseThrow();

    assertThat(user.id()).isEqualTo(1L);
    assertThat(user.name()).isEqualTo("Siva");
    assertThat(user.email()).isEqualTo("siva@gmail.com");
  }
}

Here's what the test does:

  • @SpringBootTest loads the entire application context, so UserRepository is injected directly.
  • @Testcontainers and @Container manage the PostgreSQL container lifecycle.
  • @ServiceConnection auto-configures the datasource properties from the running container, replacing the need for @DynamicPropertySource.
  • @Sql("/test-data.sql") initializes the test data.

Test PostRepository

Test the PostRepository that fetches complex object graphs using the Testcontainers special JDBC URL.

Create PostRepositoryTest.java:

package com.testcontainers.demo.domain;

import static org.assertj.core.api.Assertions.assertThat;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.jdbc.Sql;

@SpringBootTest(
  properties = {
    "spring.test.database.replace=none",
    "spring.datasource.url=jdbc:tc:postgresql:16-alpine:///db",
  }
)
@Sql("/test-data.sql")
class PostRepositoryTest {

  @Autowired
  PostRepository repository;

  @Test
  void shouldGetPostById() {
    Post post = repository.getPostById(1L).orElseThrow();

    assertThat(post.id()).isEqualTo(1L);
    assertThat(post.title()).isEqualTo("Post 1 Title");
    assertThat(post.content()).isEqualTo("Post 1 content");
    assertThat(post.createdBy().id()).isEqualTo(1L);
    assertThat(post.createdBy().name()).isEqualTo("Siva");
    assertThat(post.createdBy().email()).isEqualTo("siva@gmail.com");
    assertThat(post.comments()).hasSize(2);
  }
}

This test verifies that getPostById loads the post along with its creator and comments in a single query using jOOQ's MULTISET feature.

Run tests and next steps »