Proof of concept for using the DynamicPropertySource spring annotation in tests requiring PostgreSQL

This simple project shows how to work with the newly introduced org.springframework.test.context.DynamicPropertySource annotation which can be used in spring tests that make use of testcontainers.

Details about the process that led to the introduction of the DynamicPropertySource annotation can be found in the Github issue:

spring-projects/spring-framework#24540

Before introducing this annotation, in order to interact via spring boot with a data source (backed by a test container) that was mapped via the spring.datasource in the application.yml file (for triggering via org.springframework.boot.autoconfigure.jdbc.DataSourceInitializationConfiguration the creation of the much needed spring bean instance of type javax.sql.DataSource for JDBC/JPA tests), there was needed an implementation of the ApplicationContextInitializer to introduce the required properties in the configurable application context:

@SpringJUnitConfig(classes = {Application.class}, initializers = {PostgresIntegrationTest.Initializer.class})
@Testcontainers
public class PostgresIntegrationTest {

  @Container
  public static PostgreSQLContainer postgreSQLContainer = new PostgreSQLContainer("postgres:12")
      .withDatabaseName("integration-tests-db")
      .withUsername("sa")
      .withPassword("sa");


  @Autowired
  private JdbcTemplate jdbcTemplate;

  static class Initializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
    public void initialize(ConfigurableApplicationContext configurableApplicationContext) {
      TestPropertyValues.of(
          "spring.datasource.url=" + postgreSQLContainer.getJdbcUrl(),
          "spring.datasource.username=" + postgreSQLContainer.getUsername(),
          "spring.datasource.password=" + postgreSQLContainer.getPassword()
      ).applyTo(configurableApplicationContext.getEnvironment());
    }
  }
 
  @Test
  public void demo(){
     jdbcTemplate.execute("SELECT 1");
  }
}

With the introduction of the @DynamicPropertySource there is no need for an extra ApplicationContextInitializer:

@SpringJUnitConfig(classes = {Application.class})
@Testcontainers
public class PostgresIntegrationTest {

  @Container
  public static PostgreSQLContainer postgreSQLContainer = new PostgreSQLContainer("postgres:12")
      .withDatabaseName("integration-tests-db")
      .withUsername("sa")
      .withPassword("sa");


  @Autowired
  private JdbcTemplate jdbcTemplate;

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

  @Test
  public void demo() {
    jdbcTemplate.execute("SELECT 1");
  }
}

As can be seen from above, the newly introduced @DynamicPropertySource is somehow similar to the commonly used @TestPropertySource annotation with the mention that it allows the usage of dynamic resources such as the IP and port assigned to the container (needed in the jdbcUrl in the example above).

Check out the full source code (and corresponding documentation) of the PostgresIntegrationTest.java class.

See details about the usage of the @DynamicPropertyResource in the Spring framework documentation.