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Table of Contents

Author: Oleksandr_Dekin

Introduction

Testcontainers is a Java library that supports JUnit tests, providing lightweight, throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.

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Integration test with JUnit 4.12 and Spring Boot < 2.2.6

Code Block

language	java
title	Using: JUnit 4.12 and Spring Boot < 2.2.6

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@ContextConfiguration(initializers = IntegrationTest.Initializer.class)
public class ApplicationIT {

    @ClassRule
    public static PostgreSQLContainer postgreSQLContainer = new PostgreSQLContainer().withPassword("inmemory")
            .withUsername("inmemory");

    public static class Initializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {

        @Override
        public void initialize(ConfigurableApplicationContext configurableApplicationContext) {
            TestPropertyValues values = TestPropertyValues.of(
                    "spring.datasource.url=" + postgreSQLContainer.getJdbcUrl(),
                    "spring.datasource.password=" + postgreSQLContainer.getPassword(),
                    "spring.datasource.username=" + postgreSQLContainer.getUsername()
            );
            values.applyTo(configurableApplicationContext);
        }
    }

    @Ŧest
    public void contextLoads() {
    }
}

Integration test with JUnit 5 and Spring Boot < 2.2.6

If your application makes use of JUnit 5 but is using a Spring Boot version < 2.2.6, you don't have access to the @DynamicPropertySource feature.
A possible integration test to verify a REST API endpoint is working as expected looks like the following:

Code Block

language	java
title	JUnit 5 example with Spring Boot < 2.2.6

// JUnit 5 example with Spring Boot < 2.2.6
@Testcontainers
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
@ContextConfiguration(initializers = DeletePersonIT.Initializer.class)
public class DeletePersonIT {
 
  @Container
  public static PostgreSQLContainer postgreSQLContainer = new PostgreSQLContainer()
    .withPassword("inmemory")
    .withUsername("inmemory");
 
  @Autowired
  private PersonRepository personRepository;
 
  @Autowired
  public TestRestTemplate testRestTemplate;
 
  public static class Initializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
 
    @Override
    public void initialize(ConfigurableApplicationContext configurableApplicationContext) {
      TestPropertyValues values = TestPropertyValues.of(
        "spring.datasource.url=" + postgreSQLContainer.getJdbcUrl(),
        "spring.datasource.password=" + postgreSQLContainer.getPassword(),
        "spring.datasource.username=" + postgreSQLContainer.getUsername()
      );
      values.applyTo(configurableApplicationContext);
    }
  }
 
  @Test
  @Sql("/testdata/FILL_FOUR_PERSONS.sql")
  public void testDeletePerson() {
    testRestTemplate.delete("/api/persons/1");
    assertEquals(3, personRepository.findAll().size());
    assertFalse(personRepository.findAll().contains("Phil"));
 
  }
}

Basic application integration test with JUnit 5 and Spring Boot >= 2.2.6

If your application uses JUnit 5, you can't use the @ClassRule anymore. Fortunately, Testcontainers provides a solution to write tests with JUnit Jupiter:

Code Block

language	java
title	junit-jupiter

<dependency>
  <groupId>org.testcontainers</groupId>
  <artifactId>junit-jupiter</artifactId>
  <version>${testcontainers.version}</version>
  <scope>test</scope>
</dependency>

With this dependency and a more recent version of Spring Boot (> 2.2.6) the basic integration test looks like the following:

Code Block

language	java
title	JUnit 5 example with Spring Boot >= 2.2.6

// JUnit 5 example with Spring Boot >= 2.2.6
@Testcontainers
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
public class ApplicationIT {
 
  @Container
  public static PostgreSQLContainer postgreSQLContainer = new PostgreSQLContainer()
    .withPassword("inmemory")
    .withUsername("inmemory");
 
  @DynamicPropertySource
  static void postgresqlProperties(DynamicPropertyRegistry registry) {
    registry.add("spring.datasource.url", postgreSQLContainer::getJdbcUrl);
    registry.add("spring.datasource.password", postgreSQLContainer::getPassword);
    registry.add("spring.datasource.username", postgreSQLContainer::getUsername);
  }
 
  @Test
  public void contextLoads() {
  }
}

...

Now, we can extend and write test:

Code Block

language	java
title	GuestUserControllerITFooControllerIT
collapse	true

@Log4j2
class FooControllerIT extends BaseIntegrationTest {

  @Test
  void testFoo() throws Exception {
    //...
  }
  
  //...
}

NOTE: @DirtiesContext - SpringBootTest is reusing Spring context between tests so there is a common Hikari Pool between tests. But in the background testcontainers killed (after the previous test) a container and created a new one (before the next test). SpringBootTest is not aware of that change resulting in a new Postgres container so Hikari Pool is the same as in the previous test (pointing to already used and currently unavailable port). For reusing testcontainers we can add annotation @DirtiesContext

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Versions Compared

Old Version 3

New Version 4

Key

Introduction

Integration test with JUnit 4.12 and Spring Boot < 2.2.6

Integration test with JUnit 5 and Spring Boot < 2.2.6

Basic application integration test with JUnit 5 and Spring Boot >= 2.2.6