How to reuse Testcontainers between multiple SpringBootTests?

Question

I'm using TestContainers with Spring Boot to run unit tests for repositories like this:

@Testcontainers
@ExtendWith(SpringExtension.class)
@ActiveProfiles("itest")
@SpringBootTest(classes = RouteTestingCheapRouteDetector.class)
@ContextConfiguration(initializers = AlwaysFailingRouteRepositoryShould.Initializer.class)
@TestExecutionListeners(listeners = DependencyInjectionTestExecutionListener.class)
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
@Tag("docker")
@Tag("database")
class AlwaysFailingRouteRepositoryShould {

  @SuppressWarnings("rawtypes")
  @Container
  private static final PostgreSQLContainer database =
      new PostgreSQLContainer("postgres:9.6")
          .withDatabaseName("database")
          .withUsername("postgres")
          .withPassword("postgres");

But now I have 14 of these tests and every time a test is run a new instance of Postgres is spun up. Is it possible to reuse the same instance across all tests? The Singleton pattern doesn't help since every test starts a new application.

I've also tried testcontainers.reuse.enable=true in .testcontainers.properties and .withReuse(true), but that didn't help.

Answer 1

You can't use the JUnit Jupiter annotation @Container if you want to have reusable containers. This annotation ensures to stop the container after each test.

What you need is the singleton container approach, and use e.g. @BeforeAll to start your containers. Even though you then have .start() in multiple tests, Testcontainers won't start a new container if you opted-in for reusability using both .withReuse(true) on your container definition AND the following .testcontainers.properties file in your home directory:

testcontainers.reuse.enable=true

A simple example might look like the following:

@SpringBootTest
public class SomeIT {

  public static GenericContainer postgreSQLContainer = new PostgreSQLContainer().
    withReuse(true);

  @BeforeAll
  public static void beforeAll() {
    postgreSQLContainer.start();
  }

  @Test
  public void test() {

  }

}

and another integration test:

@SpringBootTest
public class SecondIT {

  public static GenericContainer postgreSQLContainer = new PostgreSQLContainer().
    withReuse(true);

  @BeforeAll
  public static void beforeAll() {
    postgreSQLContainer.start();
  }

  @Test
  public void secondTest() {

  }

}

There is currently a PR that adds documentation about this

I've put together a blog post explaining how to reuse containers with Testcontainers in detail.

Answer 2

If you decide go forward with the singleton pattern, mind the warning in "Database containers launched via JDBC URL scheme". I took hours till I note that, even though I was using the singleton pattern, an additional container was always being created mapped on a different port.

In summary, do not use the test containers JDBC (host-less) URIs, such as jdbc:tc:postgresql:<image-tag>:///<databasename>, if you need use the singleton pattern.